Organic solvent-free film-forming compositions, multi-layer composite coatings, and related methods

ABSTRACT

Provided is a film-forming composition substantially free of organic solvent which includes an aqueous dispersion of polymeric microparticles prepared by emulsion polymerization of a monomeric composition containing (1) at least 10 percent by weight of one or more vinyl aromatic compounds; (2) 0.1 to 10 percent by weight of one or more carboxylic acid functional polymerizable, ethylenically unsaturated monomers; (3) 0 to 10 percent by weight of one or more polymerizable monomers having one or more functional groups capable of reacting to form crosslinks; and (4) one or more polymerizable ethylenically unsaturated monomers. Each of (1), (2), (3) and (4) are different one from the other and at least one of (3) and (4) is present in the monomeric composition. Multi-layer composite coatings and coated substrates also are provided.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of U.S. patent application Ser. No.10/841,659, filed on May 7, 2004.

This application is related to U.S. patent application Ser. No.10/841,662, entitled, “Film-Forming Composition Substantially Free ofOrganic Solvent, Multi-Layer Composite Coatings and Methods RelatedThereto” filed May 7, 2004.

FIELD OF THE INVENTION

The present invention relates to substantially organic solvent free,film-forming compositions, as well as to multi-layer composite coatingsformed from such compositions which are particularly useful asautomotive coatings.

BACKGROUND INFORMATION

Color-plus-clear coating systems formed from the application of atransparent topcoat over a colored basecoat have become increasinglypopular in the coating industry, particularly for use in coatingautomobiles. The most economically attractive color-plus-clear systemsare those in which the clear coat composition can be applied directlyover the uncured colored base coat. The process of applying one layer ofa coating before the previous layer is cured, then simultaneously curingboth layers, is referred to as a wet-on-wet (“WOW”) application.Color-plus-clear coating systems suitable for WOW application provide asubstantial energy cost savings advantage.

Over the past decade, there has been an effort to reduce atmosphericpollution caused by volatile solvents which are emitted during thepainting process. However, it is often difficult to achieve highquality, smooth coating finishes, particularly clear coating finishes,such as are required in the automotive industry, without includingorganic solvents which contribute greatly to flow and leveling of acoating. Organic solvents also can be selected to control rheology ofthe coating as it is applied, particularly on vertical surfaces. Bycontrast, water-based coatings which contain little or no organicsolvent can exhibit “sagging” or running upon application especially ina high humidity environment. Moreover, in addition to achievingnear-flawless appearance, automotive coatings must be durable and chipresistant, yet economical and easy to apply.

Recently, to facilitate throughput in some automotive assembly plants,manufacturers have demanded that the primer-surfacer coating be appliedin one coat, as opposed to the conventional two-coat application. Theone-coat application can simplify the coating process and reduce capitalinvestment by elimination of a spray booth and related equipment fromthe coating line. However, in a one-coat application, to achieve desiredfilm-thicknesses, the primer coating composition must be applied using ahigh fluid delivery rate. When a water-based primer is applied at thesehigh fluid delivery rates, particularly in a high humidity environment(e.g., 75% relative humidity at 75° F. (23.9° C.)), a very wet filmusually is obtained and sagging or running of the applied wet coatingcan result.

The use of powder coatings to eliminate the emission of volatilesolvents during the painting process has become increasingly attractive.Powder coatings have become quite popular for use in coatings forautomotive components, for example, wheels, axle parts, seat frames andthe like. Use of powder coatings for clear coats in color-plus-clearsystems, however, is somewhat less prevalent for several reasons. First,powder coatings require a different application technology thanconventional liquid coating compositions and, thus, require expensivemodifications to existing application lines. Also, most automotivetopcoating compositions typically are cured at temperatures below 140°C. By contrast, most powder coating formulations require a much highercuring temperature. Further, many powder coating compositions tend toyellow more readily than conventional liquid, coating compositions, andgenerally result in coatings having a high cured film thickness, oftenranging from 60 to 70 microns.

Powder coatings in slurry form for automotive coatings can overcome manyof the disadvantages of dry powder coatings, however, powder slurrycompositions can be unstable and settle upon storage at temperaturesabove 20° C. Further, WOW application of powder slurry clear coatingcompositions over conventional base coats can result in mud-cracking ofthe system upon curing. See Aktueller Status bei derPulverlackentwickluna fur die Automobilindustrie am Beispiel fuller undKlarlack, presented by Dr. W. Kries at the 1st International Conferenceof Car-Body Powder Coatings, Berlin, Germany, Jun. 22-23, 1998,reprinted in Focus on Powder Coatings, The Royal Society of Chemistry,Sep. 2-8, 1998.

Some aqueous dispersions are known to form powder coatings uponapplication at ambient temperatures. Although applied as conventionalwaterborne coating compositions, these dispersions form powder coatingsat ambient temperature which require a ramped bake prior to undergoingconventional curing conditions in order to effect a coalesced andcontinuous film on the substrate surface. Also, many waterborne coatingcompositions contain a substantial amount of organic solvent to provideflow and coalescence of the applied coating.

The automotive industry would derive a significant economic benefit froman essentially organic solvent-free coating composition which meets thestringent automotive appearance and performance requirements, whilemaintaining ease of application and properties, such as sag and craterresistance. Also, it would be advantageous to provide an organicsolvent-free clear coat composition which can be applied by conventionalapplication means over an uncured pigmented base coating composition(i.e., via WOW application) to form a generally continuous film atambient temperature which provides a cured film free of mud-cracking.

SUMMARY OF THE INVENTION

The present invention is directed to a film-forming composition that issubstantially free of organic solvent. The film-forming compositioncomprises an aqueous dispersion of polymeric microparticles prepared byemulsion polymerization of a monomeric composition comprising: (1) atleast 10 percent by weight of one or more vinyl aromatic compounds; (2)0.1 to 10 percent by weight of one or more carboxylic acid functionalpolymerizable, ethylenically unsaturated monomers; (3) 0 to 10 percentby weight of one or more polymerizable monomers having one or morefunctional groups which are capable of reacting to form crosslinks; and(4) one or more polymerizable ethylenically unsaturated monomers, wherethe weight percentages are based on total weight of monomers present inthe monomeric composition, wherein each of (1), (2), (3) and (4) aredifferent one from the other, and wherein at least one of (3) and (4) ispresent in the monomeric composition.

The present invention also is directed to a multi-layer compositecoating comprising a basecoat deposited from at least one basecoatfilm-forming composition, and a topcoat composition applied over atleast a portion of the base coat in which the topcoat is deposited fromat least one topcoat film forming composition, wherein at least one ofthe basecoat and topcoat is formed from the film-forming composition

Substrates coated with the aforementioned compositions and compositecoatings are also provided.

DETAILED DESCRIPTION OF THE INVENTION

For purposes of the following detailed description, it is to beunderstood that the invention may assume various alternative variationsand step sequences, except where expressly specified to the contrary. Itis also to be understood that the specific devices and processes aresimply exemplary embodiments of the invention. Hence, specificdimensions and other physical characteristics related to the embodimentsdisclosed herein are not to be considered as limiting. Moreover, otherthan in any operating examples, or where otherwise indicated, allnumbers expressing, for example, quantities of ingredients used in thespecification and claims are to be understood as being modified in allinstances by the term “about”. Accordingly, unless indicated to thecontrary, the numerical parameters set forth in the followingspecification and attached claims are approximations that may varydepending upon the desired properties to be obtained by the presentinvention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements.

Also, it should be understood that any numerical range recited herein isintended to include all sub-ranges subsumed therein. For example, arange of “1 to 10” is intended to include all sub-ranges between (andincluding) the recited minimum value of 1 and the recited maximum valueof 10, that is, having a minimum value equal to or greater than 1 and amaximum value of equal to or less than 10.

The film-forming composition of the present invention is substantiallyfree of organic solvent. As used herein, including the claims, the term“substantially free of organic solvent” means that the amount of organicsolvent present in the film-forming composition is less than 10 weightpercent based on total weight of the film-forming composition. In anembodiment of the present invention, the amount of organic solventpresent in the film-forming composition can be less than 5 weightpercent, or less than 2 weight percent, where weight percentages arebased on total weight of the film-forming composition. It should beunderstood, however, that a small amount of organic solvent can bepresent in the composition, for example, to improve flow and leveling ofthe applied composition or to decrease viscosity as needed.

The film-forming composition comprises an aqueous dispersion ofpolymeric microparticles prepared by emulsion polymerization techniques,as are well known in the art, from a monomeric composition comprising(1) at least 10 percent by weight of one or more vinyl aromaticcompounds; (2) 0.1 to 10 percent by weight of one or more carboxylicacid functional polymerizable, ethylenically unsaturated monomers; (3) 0to 10 percent by weight of one or more polymerizable monomers having oneor more functional groups which are capable of reacting to formcrosslinks; and (4) one or more polymerizable ethylenically unsaturatedmonomers, where the weight percentages are based on total weight ofmonomers present in the monomeric composition. Each of (1), (2), (3) and(4) above are different one from the other, and at least one of themonomers (3) and (4) is present in the monomeric composition.

As used herein, the phrase, “different one from the other” refers tocomponents which do not have the same chemical structure as the othercomponents in the composition.

The vinyl aromatic compound (1) can comprise any suitable vinyl aromaticcompound known in the art. In an embodiment of the present invention,the one or more vinyl aromatic compounds (1) can comprise a compoundselected from styrene, alpha-methyl styrene, vinyl toluene, para-hydroxystyrene, and mixtures thereof. In a particular embodiment of the presentinvention, the vinyl aromatic compound (1) comprises styrene.

The vinyl aromatic compound (1) can be present in the monomericcomposition from which the polymeric microparticles are prepared in anamount of at least 10 percent by weight, or at least 20 percent byweight, or at least 30 percent by weight, or at least 40 percent byweight based on total weight of monomers present in the monomericcomposition. The vinyl aromatic compound (1) also can be present in themonomeric composition from which the polymeric microparticles areprepared in an amount of not more than 98 percent by weight, or not morethan 80 percent by weight, or not more than 70 percent by weight, or notmore than 60 percent by weight based on total weight of monomers presentin the monomeric composition. The amount of vinyl aromatic compound (1)present in the monomeric composition can range between any combinationof the recited values, inclusive of the recited values. It will beunderstood by those skilled in the art that the amount of the vinylaromatic compound (1) used to prepare the polymeric microparticles isdetermined by the properties desired to be incorporated into theresulting polymeric microparticles and/or the compositions containingsuch microparticles.

The one or more carboxylic acid functional, polymerizable, ethylenicallyunsaturated monomers (2) from which the polymeric microparticles areprepared can comprise any of the ethylenically unsaturated carboxylicacid functional monomers known in the art, including, where applicable,anhydrides thereof. In an embodiment of the present invention, thecarboxylic acid functional, polymerizable, ethylenically unsaturatedmonomer (2) can comprise one or more monomers selected from acrylicacid, methacrylic acid, itaconic acid, fumaric acid, maleic acid,anhydrides thereof (where applicable), and mixtures thereof.Non-limiting examples of anhydrides suitable for use as the one or morecarboxylic acid functional, polymerizable, ethylenically unsaturatedmonomers (2) can include maleic anhydride, fumaric anhydride, itaconicanhydride, methacrylic anhydride, and mixtures thereof.

The one or more carboxylic acid functional, polymerizable, ethylenicallyunsaturated monomers (2) can be present in the monomeric compositionfrom which the polymeric microparticles are prepared in an amount of 0.1percent by weight, or at least 0.5 percent by weight, or at least 1percent by weight, based on total weight of monomers present in themonomeric composition. The carboxylic acid functional, polymerizable,ethylenically unsaturated monomer (2) also can be present in themonomeric composition from which the polymeric microparticles areprepared in an amount of not more than 10 percent by weight, or not morethan 8 percent by weight, or not more than 5 percent by weight, based ontotal weight of monomers present in the monomeric composition. Theamount of the one or more carboxylic acid functional, polymerizable,ethylenically unsaturated monomers (2) present in the monomericcomposition can range between any combination of the recited values,inclusive of the recited values. It will be understood by those skilledin the art that the amount of the one or more carboxylic acidfunctional, polymerizable, ethylenically unsaturated monomers (2) usedto prepare the polymeric microparticles is determined by the propertiesdesired to be incorporated into the resultant polymeric microparticlesand/or the compositions containing such microparticles.

The one or more polymerizable monomer(s) (3) having one or morefunctional groups which are capable of reacting to form crosslinks caninclude any of the art recognized polymerizable monomers that havereactive functional groups capable of reacting either during thepolymerization process with a mutually reactive functional group(s)present on any of the other monomers present in the monomericcomposition, or, alternatively, after the monomer has been polymerized,for example, with mutually reactive functional groups present on one ormore of the film-forming composition components. As used herein,“functional groups that are capable of reacting to form crosslinks afterpolymerization” refer to, for example, functional groups on a firstpolymer molecule that may react under appropriate conditions to formcovalent bonds with mutually reactive functional groups on a secondpolymer molecule, for example a crosslinking agent molecule, ordifferent polymer molecules present in the film-forming composition.

In an embodiment of the present invention, the one or more polymerizablemonomers (3) having functional groups capable of reacting to formcrosslinks can comprise any of a variety of reactive functional groupsincluding, but not limited to, those selected from amide groups,hydroxyl groups, amino groups, epoxy groups, thiol groups, isocyanategroups, carbamate groups, and mixtures thereof.

In another embodiment of the present invention, the one or morepolymerizable monomer(s) (3) having functional groups which are capableof reacting to form crosslinks can comprise a compound selected fromN-alkoxymethyl amides, N-methylolamides, lactones, lactams, mercaptans,hydroxyls, epoxides, and the like. Examples of such monomers include,but are not limited to γ-(meth)acryloxytrialkoxysilane,N-methylol(meth)acrylamide, N-butoxymethyl(meth)acrylamide,(meth)acryliclactones, N-substituted (meth)acrylamide lactones,(meth)acryliclactams, N-substituted (meth)acrylamide lactams, glycidyl(meth)acrylate, allyl glycidyl ether, and mixtures thereof.

The one or more polymerizable monomer(s) (3) having functional groupswhich are capable of reacting to form crosslinks can be present in themonomeric composition from which the polymeric microparticles areprepared in an amount of 0 percent by weight, or at least 0.5 percent byweight, or at least 1 percent by weight, based on total weight ofmonomers present in the monomeric composition. The one or morepolymerizable monomer(s) (3) having functional groups which are capableof reacting to form crosslinks also can be present in the monomericcomposition from which the polymeric microparticles are prepared in anamount of not more than 10 percent by weight, or not more than 8 percentby weight, or not more than 5 percent by weight based on total weight ofmonomers present in the monomeric composition. The amount of the one ormore polymerizable monomer(s) (3) having functional groups which arecapable of reacting to form crosslinks present in the monomericcomposition can range between any combination of the recited values,inclusive of the recited values. It will be understood by those skilledin the art that the amount of the one or more polymerizable monomer(s)(3) having functional groups which are capable of reacting to formcrosslinks used to prepare the polymeric microparticles is determined bythe properties desired to be incorporated into the resultant polymericmicroparticles and/or the film-forming compositions containing suchmicroparticles.

The one or more polymerizable ethylenically unsaturated monomer (4) canbe any of the art recognized ethylenically unsaturated monomers,provided that the polymerizable ethylenically unsaturated monomer (4) isdifferent from any of the aforementioned monomers (1), (2), and (3).Polymerizable ethylenically unsaturated monomers suitable for use as themonomer (4) which are different from the monomers (1), (2) and (3), mayinclude any suitable polymerizable ethylenically unsaturated monomercapable of being polymerized in a emulsion polymerization system anddoes not substantially affect the stability of the emulsion or thepolymerization process.

Suitable polymerizable ethylenically unsaturated monomers can include,but are not limited to, alkyl esters of (meth)acrylic acid such asmethyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate,N-butyl(meth)acrylate, t-butyl(meth)acrylate,2-ethylhexyl(meth)acrylate, isobornyl (meth)acrylate, lauryl(meth)acrylate, cyclohexyl (meth)acrylate, and 3,3,5-trimethylcyclohexyl(meth)acrylate.

The one or more polymerizable ethylenically unsaturated monomers (4)also can include hydroxy-functional ethylenically unsaturated monomers,for example, a compound selected from hydroxyethyl (meth)acrylate,hydroxybutyl (meth)acrylate, hydroxypropyl(meth)acrylate,dimethylaminoethyl (meth)acrylate, allyl glycerol ether, methallylglycerol ether, and mixtures thereof.

As used herein, in the specification and the claims, “(meth)acrylate”and like terms is intended to include both acrylates and methacrylates.

In a one embodiment of the present invention, the one or morepolymerizable ethylenically unsaturated monomers (4) can comprise one ormore ethylenically unsaturated, beta-hydroxy ester functional monomers.Such monomers can be derived from the reaction of an ethylenicallyunsaturated acid functional monomer, such as any of the monocarboxylicacids described above, e.g., acrylic acid, and an epoxy compound whichdoes not participate in the free radical initiated polymerization withsuch unsaturated acid functional monomer. Examples of such epoxycompounds include glycidyl ethers and esters. Suitable glycidyl ethersinclude glycidyl ethers of alcohols and phenols such as butyl glycidylether, octyl glycidyl ether, phenyl glycidyl ether and the like.Suitable glycidyl esters include those commercially available from ShellChemical Company under the tradename CARDURA E; and from Exxon ChemicalCompany under the tradename GLYDEXX-10. Alternatively, the beta-hydroxyester functional monomers can be prepared from an ethylenicallyunsaturated, epoxy functional monomer, for example glycidyl(meth)acrylate and allyl glycidyl ether, and a saturated carboxylicacid, such as a saturated monocarboxylic acid, for example isostearicacid.

The one or more ethylenically unsaturated polymerizable monomers (4) canbe present in the monomeric composition from which the polymericmicroparticles are prepared in an amount of 0 percent by weight, or atleast 0.5 percent by weight, or at least 1 percent by weight, or atleast 10 weight percent, or at least 20 weight percent based on totalweight of monomers present in the monomeric composition. The one or moreethylenically unsaturated polymerizable monomers (4) also can be presentin the monomeric composition from which the polymeric microparticles areprepared in an amount of not more than 60 percent by weight, or not morethan 50 percent by weight, or not more than 45 percent by weight, or notmore than 40 percent by weight based on total weight of monomers presentin the monomeric composition. The amount of the one or moreethylenically unsaturated polymerizable monomers (4) present in themonomeric composition can range between any combination of the recitedvalues, inclusive of the recited values. It will be understood by thoseskilled in the art that the amount of the one or more ethylenicallyunsaturated polymerizable monomers (4) used to prepare the polymericmicroparticles is determined by the properties desired to beincorporated into the resultant polymeric microparticles and/or thefilm-forming compositions comprising such microparticles.

In an embodiment of the present invention, the one or more ethylenicallyunsaturated polymerizable monomers (4) can comprise a crosslinkingmonomer having two or more sites of reactive unsaturation, or any of thepreviously mentioned monomers having functional groups capable ofreacting to form a crosslink after polymerization. Suitable monomershaving two or more sites of reactive unsaturation can include, but arenot limited to, one or more of ethylene glycol di(meth)acrylate,triethylene glycol di(meth)acrylate, tetraethylene glycoldi(meth)acrylate, 1,3-butylene glycol di(meth)acrylate,trimethylolpropane tri(meth)acrylate, 1,4-butanediol di(meth)acrylate,neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate,pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate,pentaerythritol tetra(meth)acrylate, glycerol di(meth)acrylate, glycerolallyloxy di(meth)acrylate, 1,1,1-tris(hydroxymethyl)ethanedi(meth)acrylate, 1,1,1-tris(hydroxymethyl)ethane tri(meth)acrylate,1,1,1-tris(hydroxymethyl)propane di(meth)acrylate,1,1,1-tris(hydroxymethyl)propane tri(meth)acrylate, triallyl cyanurate,triallyl isocyanurate, triallyl trimellitate, diallyl phthalate, diallylterephthalte, divinyl benzene, methylol (meth)acrylamide, triallylamine,and methylenebis (meth) acrylamide.

As mentioned above, the aqueous dispersion of polymeric microparticlesis prepared by well-known emulsion polymerization techniques. Forexample the monomeric composition can be prepared by admixing monomer(s)(1), with monomers (2) and/or (3) and/or (4). The monomeric compositionis dispersed in the aqueous continuous phase under high shear to formstable monomer droplets and/or micelles as would be expected undertypical emulsion polymerization techniques. Emulsifiers, protectivecolloids, and/or surface active agents as are well known in the art maybe included to stabilize or prevent coagulation or agglomeration of themonomer droplets during the polymerization process. The aqueousdispersion is then subjected to radical polymerization conditions topolymerize the monomers within the droplets or micelles.

Suitable emulsifiers and protective colloids include, but are notlimited to high molecular weight polymers such as hydroxyethylcellulose, methyl cellulose, polyacrylic acid, polyvinyl alcohol, andthe like. Also, materials such as base-neutralized acid functionalpolymers can be employed for this purpose. Suitable surface activeagents can include any of the well known anionic, cationic or nonionicsurfactants or dispersing agents. Mixtures of such materials can beused.

Suitable cationic dispersion agents include, but are not limited tolauryl pyridinium chloride, cetyldimethyl amine acetate, andalkyldimethylbenzylammonium chloride, in which the alkyl group has from8 to 18 carbon atoms. Suitable anionic dispersing agents include, butare not limited to alkali fatty alcohol sulfates, such as sodium laurylsulfate, and the like; arylalkyl sulfonates, such as potassiumisopropylbenzene sulfonate, and the like; alkali alkyl sulfosuccinates,such as sodium octyl sulfosuccinate, and the like; and alkaliarylalkylpolyethoxyethanol sulfates or sulfonates, such as sodiumoctylphenoxypolyethoxyethyl sulfate, having 1 to 5 oxyethylene units,and the like. Suitable non-ionic surface active agents include but arenot limited to alkyl phenoxypolyethoxy ethanols having alkyl groups offrom about 7 to 18 carbon atoms and from about 6 to about 60 oxyethyleneunits such as, for example, heptyl phenoxypolyethoxyethanols; ethyleneoxide derivatives of long chained carboxylic acids such as lauric acid,myristic acid, palmitic acid, oleic acid, and the like, or mixtures ofacids such as those found in tall oil containing from 6 to 60oxyethylene units; ethylene oxide condensates of long chained alcoholssuch as octyl, decyl, lauryl, or cetyl alcohols containing from 6 to 60oxyethylene units; ethylene oxide condensates of long-chain or branchedchain amines such as dodecyl amine, hexadecyl amine, and octadecylamine, containing from 6 to 60 oxyethylene units; and block copolymersof ethylene oxide sections combined with one or more hydrophobicpropylene oxide sections.

A free radical initiator typically is used in the emulsionpolymerization process. Any suitable art recognized free radicalinitiator may be used. Suitable free radical initiators include, but arenot limited to thermal initiators, photoinitiators andoxidation-reduction initiators, all of which may be otherwisecategorized as being water-soluble initiators or non-water-solubleinitiators. Examples of thermal initiators include, but are not limitedto azo compounds, peroxides and persulfates. Suitable persulfatesinclude, but are not limited to sodium persulfate and ammoniumpersulfate. Oxidation-reduction initiators may include, as non-limitingexamples persulfate-sullfite systems as well as systems utilizingthermal initiators in combination with appropriate metal ions such asiron or copper.

Suitable azo compounds include, but are not limited to non-water-solubleazo compounds such as 1-1′-azobiscyclohexanecarbonitrile),2-2′-azobisisobutyronitrile, 2-2′-azobis(2-methylbutyronitrile),2-2′-azobis(propionitrile), 2-2′-azobis(2,4-dimethylvaleronitrile),2-2′-azobis(valeronitrile), 2-(carbamoylazo)-isobutyronitrile andmixtures thereof.; and water-soluble azo compounds such as azobistertiary alkyl compounds include, but are not limited to,4-4′-azobis(4-cyanovaleric acid), 2-2′-azobis(2-methylpropionamidine)dihydrochloride, 2,2′-azobis[2-methyl-N-(2-hydroxyethyl)propionamide],4,4′-azobis(4-cyanopentanoic acid),2,2′-azobis(N,N′-dimethyleneisobutyramidine),2,2′-azobis(2-amidinopropane) dihydrochloride,2,2′-azobis(N,N′-dimethyleneisobutyramidine) dihydrochloride andmixtures thereof.

Suitable peroxides include, but are not limited to hydrogen peroxide,methyl ethyl ketone peroxides, benzoyl peroxides, di-t-butyl peroxides,di-t-amyl peroxides, dicumyl peroxides, diacyl peroxides, decanoylperoxide, lauroyl peroxide, peroxydicarbonates, peroxyesters, dialkylperoxides, hydroperoxides, peroxyketals and mixtures thereof.

In one embodiment of the present invention, the average particle size ofthe polymeric microparticles may be at least 200 Angstroms, or at least800 Angstroms, or at least 1000 Angstroms, or at least 1500 Angstroms.The average particle size of the polymeric microparticles can be no morethan 10,000 Angstroms, or not more than 8000 Angstroms, or not more than5000 Angstroms, or not more than 2500 Angstroms. When the averageparticle size is too large, the microparticles may tend to settle fromthe latex emulsion upon storage. The average particle size of thepolymeric microparticles may be any value or in any range of valuesinclusive of those stated above.

The average particle size can be measured by photon correlationspectroscopy as described in International Standard ISO 13321. Theaverage particle size values reported herein are measured by photoncorrelation spectroscopy using a Malvern Zetasizer 3000HSa according tothe following procedure. Approximately 10 mL of ultrafiltered deionizedwater and 1 drop of a homogenous test sample are added to a clean 20 mLvial and then mixed. A cuvet is cleaned and approximately half-filledwith ultrafiltered deionized water, to which about 3-6 drops of thediluted sample is added. Once any air bubbles are removed, the cuvet isplaced in the Zetasizer 3000HSa to determine if the sample is of thecorrect concentration using the Correlator Control window in theZetasizer Software (100 to 400 KCts/sec). Particle size measurements arethen made with the Zetasizer 3000HSa.

As used herein, including the claims, the term “dispersion” means thatthe microparticles are capable of being distributed throughout water asfinely divided particles, such as a latex. See Hawley's CondensedChemical Dictionary, (12th Ed. 1993) at page 435, which is herebyincorporated by reference. The uniformity of the dispersion can beincreased by the addition of wetting, dispersing or emulsifying agents(surfactants), which are discussed above.

As previously mentioned, the aqueous dispersion of polymericmicroparticles prepared by emulsion polymerization described above canbe used as a component in a film-forming composition that issubstantially free of organic solvent. The aqueous dispersion ofpolymeric microparticles prepared by emulsion polymerization can bepresent in the film-forming composition in an amount of at least 1percent by weight, or at least 2 percent by weight, or at least 5percent by weight, based on total weight of resin solids present in thefilm-forming composition. Also, the aqueous dispersion of polymericmicroparticles prepared by emulsion polymerization can be present in thefilm-forming composition in an amount of not more than 20 percent byweight, or not more than 15 percent by weight, or not more than 10percent by weight. The amount of the aqueous dispersion of polymericmicroparticles prepared by emulsion polymerization present in thefilm-forming composition can range between any combination of thesevalues inclusive of the recited values.

The substantially organic solvent-free film-forming composition of thepresent invention can be a thermoplastic film-forming composition, or,alternatively, a thermosetting composition. As used herein, by“thermosetting composition” is meant one which “sets” irreversibly uponcuring or crosslinking, wherein the polymer chains of the polymericcomponents are joined together by covalent bonds. This property isusually associated with a cross-linking reaction of the compositionconstituents often induced, for example, by heat or radiation. Hawley,Gessner G., The Condensed Chemical Dictionary, Ninth Edition., page 856;Surface Coatings, vol. 2, Oil and Colour Chemists' Association,Australia, TAFE Educational Books (1974). Curing or crosslinkingreactions also may be carried out under ambient conditions. Once curedor crosslinked, a thermosetting composition will not melt upon theapplication of heat and is insoluble in solvents. By contrast, a“thermoplastic composition” comprises polymeric components which are notjoined by covalent bonds and thereby can undergo liquid flow uponheating and are soluble in solvents. Saunders, K. J., Organic PolymerChemistry, pp. 41-42, Chapman and Hall, London (1973).

In an embodiment of the present invention the film-forming compositioncomprises, in addition to the aqueous dispersion of polymericmicroparticles prepared by emulsion polymerization, any of the secondaqueous dispersions of polymeric microparticles described below.

In an embodiment of the present invention, the film-forming compositioncomprises a thermosetting composition which comprises, in addition tothe aqueous dispersion of polymeric microparticles prepared by emulsionpolymerization described in detail above, a resinous binder systemtypically comprising (a) at least one reactive functionalgroup-containing polymer, and (b) at least one crosslinking agent havingfunctional groups reactive with the functional groups of the polymer.The functional groups of the crosslinking agent also may be reactivewith any reactive functional groups present in the above-describedpolymeric microparticles.

The functional group-containing polymer (a) can comprise any of avariety of reactive group-containing polymers well known in the surfacecoatings art provided the polymer is sufficiently dispersible in aqueousmedia. Suitable non-limiting examples can include acrylic polymers,polyester polymers, polyurethane polymers, polyether polymers,polysiloxane polymers, polyepoxide polymers, copolymers thereof, andmixtures thereof. Also, the polymer (a) can comprise a variety ofreactive functional groups, for example, functional groups selected fromat least one of hydroxyl groups, carboxyl groups, epoxy groups, aminogroups, amido groups, carbamate groups, isocyanate groups, andcombinations thereof.

For example, suitable hydroxyl group-containing polymers can includeacrylic polyols, polyester polyols, polyurethane polyols, polyetherpolyols, and mixtures thereof.

Suitable hydroxyl group and/or carboxyl group-containing acrylicpolymers can be prepared from polymerizable ethylenically unsaturatedmonomers and are typically copolymers of (meth)acrylic acid and/orhydroxylalkyl esters of (meth)acrylic acid with one or more otherpolymerizable ethylenically unsaturated monomers such as alkyl esters of(meth)acrylic acid including methyl (meth)acrylate, ethyl(meth)acrylate, butyl (meth)acrylate and 2-ethyl hexylacrylate, andvinyl aromatic compounds such as styrene, alpha-methyl styrene, andvinyl toluene.

In a one embodiment of the present invention, the acrylic polymer can beprepared from ethylenically unsaturated, beta-hydroxy ester functionalmonomers. Such as those described above.

Epoxy functional groups can be incorporated into the acrylic polymerprepared from polymerizable ethylenically unsaturated monomers bycopolymerizing oxirane group-containing monomers, for example glycidyl(meth)acrylate and allyl glycidyl ether, with other polymerizableethylenically unsaturated monomers, such as those discussed above.Preparation of such epoxy functional acrylic polymers is described indetail in U.S. Pat. No. 4,001,156 at columns 3 to 6, incorporated hereinby reference.

Carbamate functional groups can be incorporated into the acrylic polymerprepared from polymerizable ethylenically unsaturated monomers bycopolymerizing, for example, the above-described ethylenicallyunsaturated monomers with a carbamate functional vinyl monomer such as acarbamate functional alkyl ester of methacrylic acid. Useful carbamatefunctional alkyl esters can be prepared by reacting, for example, ahydroxyalkyl carbamate, such as the reaction product of ammonia andethylene carbonate or propylene carbonate, with methacrylic anhydride.Other useful carbamate functional vinyl monomers include, for instance,the reaction product of hydroxyethyl methacrylate, isophoronediisocyanate, and hydroxypropyl carbamate; or the reaction product ofhydroxypropyl methacrylate, isophorone diisocyanate, and methanol. Stillother carbamate functional vinyl monomers may be used, such as thereaction product of isocyanic acid (HNCO) with a hydroxyl functionalacrylic or methacrylic monomer such as hydroxyethyl acrylate, and thosedescribed in U.S. Pat. No. 3,479,328, incorporated herein by reference.Carbamate functional groups can also be incorporated into the acrylicpolymer by reacting a hydroxyl functional acrylic polymer with a lowmolecular weight alkyl carbamate such as methyl carbamate. Pendantcarbamate groups can also be incorporated into the acrylic polymer by a“transcarbamoylation” reaction in which a hydroxyl functional acrylicpolymer is reacted with a low molecular weight carbamate derived from analcohol or a glycol ether. The carbamate groups exchange with thehydroxyl groups yielding the carbamate functional acrylic polymer andthe original alcohol or glycol ether. Also, hydroxyl functional acrylicpolymers can be reacted with isocyanic acid to provide pendent carbamategroups. Likewise, hydroxyl functional acrylic polymers can be reactedwith urea to provide pendent carbamate groups.

The polymers prepared from polymerizable ethylenically unsaturatedmonomers can be prepared by solution polymerization techniques, whichare well-known to those skilled in the art, in the presence of suitablecatalysts such as organic peroxides or azo compounds, for example,benzoyl peroxide or N,N-azobis(isobutyronitrile). The polymerization canbe carried out in an organic solution in which the monomers are solubleby techniques conventional in the art. Alternatively, these polymers canbe prepared by aqueous emulsion or dispersion polymerization techniqueswhich are well-known in the art. The ratio of reactants and reactionconditions are selected to result in an acrylic polymer with the desiredpendent functionality.

Polyester polymers are also useful in the film-forming compositions ofthe invention. Useful polyester polymers typically include thecondensation products of polyhydric alcohols and polycarboxylic acids.Suitable polyhydric alcohols can include ethylene glycol, neopentylglycol, trimethylol propane, and pentaerythritol. Suitablepolycarboxylic acids can include adipic acid, 1,4-cyclohexyldicarboxylic acid, and hexahydrophthalic acid. Besides thepolycarboxylic acids mentioned above, functional equivalents of theacids such as anhydrides where they exist or lower alkyl esters of theacids such as the methyl esters can be used. Also, small amounts ofmonocarboxylic acids such as stearic acid can be used. The ratio ofreactants and reaction conditions are selected to result in a polyesterpolymer with the desired pendent functionality, i.e., carboxyl orhydroxyl functionality.

For example, hydroxyl group-containing polyesters can be prepared byreacting an anhydride of a dicarboxylic acid such as hexahydrophthalicanhydride with a diol such as neopentyl glycol in a 1:2 molar ratio.Where it is desired to enhance air-drying, suitable drying oil fattyacids may be used and include those derived from linseed oil, soya beanoil, tall oil, dehydrated castor oil, or tung oil.

Carbamate functional polyesters can be prepared by first forming ahydroxyalkyl carbamate that can be reacted with the polyacids andpolyols used in forming the polyester. Alternatively, terminal carbamatefunctional groups can be incorporated into the polyester by reactingisocyanic acid with a hydroxy functional polyester. Also, carbamatefunctionality can be incorporated into the polyester by reacting ahydroxyl polyester with a urea. Additionally, carbamate groups can beincorporated into the polyester by a transcarbamoylation reaction.Preparation of suitable carbamate functional group-containing polyestersare those described in U.S. Pat. No. 5,593,733 at column 2, line 40 tocolumn 4, line 9, incorporated herein by reference.

Polyurethane polymers containing terminal isocyanate or hydroxyl groupsalso can be used as the polymer (d) in the coating compositions of theinvention. The polyurethane polyols or NCO-terminated polyurethaneswhich can be used are those prepared by reacting polyols includingpolymeric polyols with polyisocyanates. Polyureas containing terminalisocyanate or primary and/or secondary amine groups which also can beused are those prepared by reacting polyamines including polymericpolyamines with polyisocyanates. The hydroxyl/isocyanate oramine/isocyanate equivalent ratio is adjusted and reaction conditionsare selected to obtain the desired terminal groups. Examples of suitablepolyisocyanates include those described in U.S. Pat. No. 4,046,729 atcolumn 5, line 26 to column 6, line 28, incorporated herein byreference. Examples of suitable polyols include those described in U.S.Pat. No. 4,046,729 at column 7, line 52 to column 10, line 35,incorporated herein by reference. Examples of suitable polyaminesinclude those described in U.S. Pat. No. 4,046,729 at column 6, line 61to column 7, line 32 and in U.S. Pat. No. 3,799,854 at column 3, lines13 to 50, both incorporated herein by reference.

Carbamate functional groups can be introduced into the polyurethanepolymers by reacting a polyisocyanate with a polyester having hydroxylfunctionality and containing pendent carbamate groups. Alternatively,the polyurethane can be prepared by reacting a polyisocyanate with apolyester polyol and a hydroxyalkyl carbamate or isocyanic acid asseparate reactants. Examples of suitable polyisocyanates are aromaticisocyanates, such as 4,4′-diphenylmethane diisocyanate, 1,3-phenylenediisocyanate and toluene diisocyanate, and aliphatic polyisocyanates,such as 1,4-tetramethylene diisocyanate and 1,6-hexamethylenediisocyanate. Cycloaliphatic diisocyanates, such as 1,4-cyclohexyldiisocyanate and isophorone diisocyanate also can be employed.

Examples of suitable polyether polyols include polyalkylene etherpolyols such as those having the following structural formulas (II):

wherein the substituent R is hydrogen or a lower alkyl group containingfrom 1 to 5 carbon atoms including mixed substituents, and n has a valuetypically ranging from 2 to 6 and m has a value ranging from 8 to 100 orhigher. Exemplary polyalkylene ether polyols includepoly(oxytetramethylene) glycols, poly(oxytetraethylene) glycols,poly(oxy-1,2-propylene) glycols, and poly(oxy-1,2-butylene) glycols.

Also useful are polyether polyols formed from oxyalkylation of variouspolyols, for example, glycols such as ethylene glycol, 1,6-hexanediol,Bisphenol A, and the like, or other higher polyols such astrimethylolpropane, pentaerythritol, and the like. Polyols of higherfunctionality which can be utilized as indicated can be made, forinstance, by oxyalkylation of compounds such as sucrose or sorbitol. Onecommonly utilized oxyalkylation method is reaction of a polyol with analkylene oxide, for example, propylene or ethylene oxide, in thepresence of an acidic or basic catalyst. Specific examples of polyethersinclude those sold under the names TERATHANE and TERACOL, available fromE.I. Du Pont de Nemours and Company, Inc.

Generally, the polymers having reactive functional groups which areuseful in the film-forming compositions of the present invention canhave a weight average molecular weight (Mw) typically ranging from 1000to 20,000, or from 1500 to 15,000 or from 2000 to 12,000 as determinedby gel permeation chromatography using a polystyrene standard.

In one embodiment of the present invention, the polymer (a) is in theform of a second aqueous dispersion comprising polymeric microparticles,which are adapted to react with a crosslinking agent.

In certain embodiments of the invention, the amount of the secondaqueous dispersion resin solids present in the film-forming compositioncan be at least 20 weight percent, or, in some embodiments, at least 30weight percent, or, in yet other embodiments, at least 40 weight percentbased on the total resin solids weight of the film-forming composition.In certain embodiments of the invention, the amount of the secondaqueous dispersion of polymeric microparticles resin solids present inthe film-forming composition also can be no more than 90 weight percent,or, in some embodiments, no more than 85 weight percent, or, in yetother embodiments, no more than 80 weight percent based on the weight oftotal resin solids present in the film-forming composition. The amountof the second aqueous dispersion of polymeric microparticles present inthe film-forming composition can range between any combination of thesevalues inclusive of the recited values. The solids content is determinedby heating a sample of the composition to 105° to 110° C. for 1 to 2hours to drive off the volatile material, and subsequently measuringrelative weight loss.

In certain embodiments of the present invention, the second aqueousdispersion of polymeric microparticles can be prepared from (i) at leastone polymer having reactive functional groups, typically a substantiallyhydrophobic polymer; and (ii) at least one crosslinking agent, typicallya substantially hydrophobic crosslinking agent, containing functionalgroups which are reactive with the functional groups of the polymer.Suitable substantially hydrophobic polymers can be prepared bypolymerizing one or more ethylenically unsaturated carboxylic acidfunctional group-containing monomers and one or more other ethylenicallyunsaturated monomers free of acid functionality, e.g., an ethylenicallyunsaturated monomer having hydroxyl and/or carbamate functional groups.Suitable substantially hydrophobic crosslinking agents can include, forexample, polyisocyanates, blocked polyisocyanates and aminoplast resins.Suitable aqueous dispersions of polymeric microparticles include thosedescribed in detail in U.S. Pat. No. 6,462,139 at column 4, line 17 tocolumn 11, line 49, which is incorporated herein by reference.

As used herein, including the claims, the term “substantiallyhydrophobic” means that the hydrophobic component is essentially notcompatible with, does not have an affinity for and/or is not capable ofdissolving in water using conventional mixing means. That is, uponmixing a sample of the hydrophobic component with an organic componentand water, a majority of the hydrophobic component is in the organicphase and a separate aqueous phase is observed. See Hawley's CondensedChemical Dictionary, (12^(th) ed. 1993) at page 618.

In certain embodiments of the present invention, the second aqueousdispersion of polymeric microparticles can be prepared from (1) one ormore reaction products of ethylenically unsaturated monomers, at leastone of which contains at least one acid functional group, (2) one ormore polymers different from (1) and (3), typically containing reactivefunctional groups, which are typically substantially hydrophobicpolymers, and (3) one or more crosslinking agents, typicallysubstantially hydrophobic crosslinking agents, having functional groupsreactive with those of the reaction product (1) and/or the polymer (2).The polymer (2) can be any of the well-known polymers such as acrylicpolymers, polyester polymers, alkyd polymers, polyurethane polymers,polyether polymers, polyurea polymers, polyamide polymers, polycarbonatepolymers, copolymers thereof and mixtures thereof. Suitablesubstantially hydrophobic crosslinking agents include, for example,polyisocyanates, blocked polyisocyanates and aminoplast resins. Suitableaqueous dispersions of polymeric microparticles include those describedin detail in U.S. Pat. No. 6,329,060 at column 4, line 27 to column 17,line 6, which is incorporated herein by reference.

In a further embodiment of the present invention, the second aqueousdispersion of polymeric microparticles can be prepared from components(A) at least one functional group-containing reaction product ofpolymerizable, ethylenically unsaturated monomers; and (B) at least onereactive organopolysiloxane. The components from which the polymericmicroparticles can be prepared may further include (C) at least onesubstantially hydrophobic crosslinking agent.

The reactive organopolysiloxane (B) typically comprises at least one ofthe following structural units (III):R¹ _(n)R² _(m)—(—Si—O)_((4-n-m)/2)  (III)where m and n each represent a positive number fulfilling therequirements of: 0<n<4; 0<m<4; and 2≦(m+n)<4; R¹ represents H, OH ormonovalent hydrocarbon groups; and R² represents a monovalent reactivefunctional group-containing organic moiety. In a particular embodimentof the present invention, R² represents a reactive group-containingmoiety selected from at least one of hydroxyl, carboxylic acid,isocyanate and blocked isocyanate, primary amine, secondary amine,amide, carbamate, urea, urethane, alkoxysilane, vinyl and epoxyfunctional groups. Suitable aqueous dispersions of polymericmicroparticles include those described in detail in U.S. Pat. No.6,387,997 at column 3, line 47 to column 14, line 54, which isincorporated herein by reference.

In an embodiment of the present invention, any of the previouslydescribed film-forming compositions can further include at least onefirst water dilutable additive comprising the reaction product of (i) areactant comprising at least one isocyanate functional group with (ii)an active hydrogen containing alkoxypolyalkylene. As used herein,including the claims, the term “water dilutable” means that the additiveis or has been adapted to be water soluble or water dispersable.

The isocyanates which are useful as reactant (i) in preparing the firstwater dilutable additive can include both monoisocyanates orpolyisocyanates, or a mixture thereof. Illustrative of themonoisocyanates are ethylenically unsaturated polymerizable monomerscontaining an isocyanato group. Illustrative of these monoisocyanatesare isocyanato alkyl esters of ethylenically unsaturated carboxylicacids such as vinyl isocyanates, allyl isocyanates, allyloxyalkylisocyanates and styryl isocyanates. Representative examples are2-isocyanato ethyl acrylate, 2-isocyanato ethyl methacrylate, propenylisocyanate, and 9-decenyl isocyanate.

Polyisocyanates useful herein for this purpose include both aliphaticand aromatic isocyanates. Representative examples include, withoutlimitation, the aliphatic isocyanates such as trimethylene,tetramethylene, pentamethylene, hexamethylene, 1,2-propylene,1,2-butylene, 2,3-butylene, and 1,3-butylene diisocyanates; thecycloalkylene compounds such as 1,3-cyclopentane, 1,4-cyclohexane,1,2-cyclohexane diisocyanates and isophorone diisocyanates; the aromaticcompounds such as m-phenylene, p-phenylene, 4,4′-diphenyl,1,5-napthalene and 1,4-naphthalene diisocyanates; the aliphatic-aromaticcompounds such as 4,4′-diphenylene methane, 2,4- or 2,6-tolylene, ormixtures thereof, 4,4′-toluidine, and 1,4-xylylene diisocyanates; thenuclear-substituted aromatic compounds such as dianisidine diisocyanate,4,4′-diphenylether diisocyanate and chlorodiphenylene diisocyanate; thetriisocyanates such as triphenyl methane-4,4′,4″-triisocyanate,1,3,5-triisocyanate benzene and 2,4,6-triisocyanate toluene; and thetetraisocyanates such as 4,4′-dimethyldiphenylmethane-2,2′,5,5′-tetraisocyanate; the polymerized polyisocyanates suchas tolylene diisocyanate dimers and trimers, and the like.

In addition, the polyisocyanates may be prepolymers derived from polyolssuch as polyether polyols or polyester polyols, including polyols whichare reacted with excess polyisocyanates, such as mentioned above, toform isocyanate-terminated prepolymers. Examples of the suitableisocyanate prepolymers are described in U.S. Pat. No. 3,799,854, column2, lines 22 to 53, which is herein incorporated by reference.

The active hydrogen containing alkoxypolyalkylenes which are useful asreactant (ii) in preparing the water dilutable additive of the presentinvention include alkoxyethylene glycols, such as, for example,methoxypolyethylene glycol, and butoxypolyethylene glycol. Also suitablefor use as reactant (ii) are polyalkoxyalkylene amines, includingpolyoxyalkylene monoamines, and polyocyalkylene polyamines, for example,polyoxyalkylene diamine and polyoxyalkylene polyamines. Specificnon-limiting examples of suitable polyoxyalkylene polyamines includepolyoxypropylene diamines commercially available under the tradenamesJEFFAMINE® D-2000 and JEFFAMINE® D-400 from Huntsman Corporation ofHouston, Tex. Mixed polyoxyalkylene polyamines, that is, those in whichthe oxyalkylene group can be selected from more than one moiety, alsocan be used as reactant (ii).

According to certain embodiments of the present invention, the firstwater dilutable additive can be present in the film forming compositionin an amount ranging from 0 up to 10 percent by weight, or in an amountranging from 1 up to 8 percent by weight, or, in yet other embodiments,in an amount ranging from 2 up to 7 percent by weight based on totalweight of resin solids present in the film-forming composition.

In certain embodiments of the present invention, the film-formingcomposition can further include, in addition to the components describedabove, at least one second water dilutable additive which is differentfrom the first water dilutable additive described above. The secondwater dilutable additive comprises a reactive functionalgroup-containing polysiloxane, for example, hydroxyl, carboxylic acidand amine functional group-containing polysiloxanes.

In accordance with certain embodiments of the present invention, thefilm-forming composition can include at least one water dilutablecarboxylic acid functional group-containing polysiloxane, such as apolysiloxane having the following general structure:

where m is at least 1; m′ is 0 to 50; n is 0 to 50; R is selected fromthe group consisting of OH and monovalent hydrocarbon groups connectedto the silicon atoms; Ra has the following structure:R¹—O—X  (VII)

wherein R¹ is alkylene, oxyalkylene or alkylene aryl; and at least one Xcontains one or more COOH functional groups.

The acid functional polysiloxane can be prepared, for example, byreacting (a) a polysiloxane polyol; and (b) at least one carboxylic acidfunctional material or anhydride. The resulting acid functional polyolis further neutralized with, for example, amine, to render the reactionproduct water dilutable.

Examples of anhydrides suitable for use in the present invention asreactant (b) immediately above include hexahydrophthalic anhydride,methyl hexahydrophthalic anhydride, phthalic anhydride, trimelliticanhydride, succinic anhydride, chlorendic anhydride, alkenyl succinicanhydride and substituted alkenyl succinic anhydride, and mixturesthereof.

According to certain embodiments of the present invention, the secondwater dilutable additive comprising a functional group-containingpolysiloxane is present in the film-forming composition in an amountranging from 0.1 up to 10.0 weight percent based on total weight ofresin solids present in the film-forming composition, or in an amountranging from 0.1 up to 5.0 weight percent or, in yet other embodiments,in an amount ranging from 0.1 to 1.0 weight percent based on the weightof total solids present in the film-forming composition.

As previously mentioned, in certain embodiments of the presentinvention, the film-forming composition may also comprise (b) one ormore crosslinking agents that are adapted to react with the functionalgroups of the polymer and/or any of the previously mentioned polymericmicroparticles and/or additives to provide curing, if desired, for thefilm-forming composition. Non-limiting examples of suitable crosslinkingagents include any of the aminoplasts and polyisocyanates as are wellknown in the surface coatings art, provided that the crosslinkingagent(s) are adapted to be water soluble or water dispersible asdescribed below, and polyacids, polyanhydrides and mixtures thereof.When used, selection of the crosslinking agent or mixture ofcrosslinking agents is dependent upon the functionality associated withthe polymeric microparticles, such as hydroxyl and/or carbamatefunctionality. When, for example, the functionality is hydroxyl, thehydrophilic crosslinking agent may be an aminoplast or polyisocyanatecrosslinking agent.

Examples of aminoplast resins suitable for use as the crosslinking agentinclude those containing methylol or similar alkylol groups, a portionof which have been etherified by reaction with a lower alcohol, such asmethanol, to provide a water soluble/dispersible aminoplast resin. Oneappropriate aminoplast resin is the partially methylated aminoplastresin, CYMEL® 385, which is commercially available from CytecIndustries, Inc. An example of a blocked isocyanate which is watersoluble/dispersible and suitable for use as the crosslinking agent isdimethyl pyrazole blocked hexamethylene diisocyanate trimer commerciallyavailable as BI 7986 from Baxenden Chemicals, Ltd. in Lancashire,England.

Polyacid crosslinking materials suitable for use in the presentinvention can include, for example, those that on average generallycontain greater than one acid group per molecule, sometimes three ormore and sometimes four or more, such acid groups being reactive withepoxy functional film-forming polymers. Polyacid crosslinking materialsmay have di-, tri- or higher functionalities. Suitable polyacidcrosslinking materials which can be used include, for example,carboxylic acid group-containing oligomers, polymers and compounds, suchas acrylic polymers, polyesters, and polyurethanes and compounds havingphosphorus-based acid groups.

Examples of suitable polyacid crosslinking agents include, for example,ester group-containing oligomers and compounds including half-estersformed from reacting polyols and cyclic 1,2-acid anhydrides or acidfunctional polyesters derived from polyols and polyacids or anhydrides.These half-esters are of relatively low molecular weight and are quitereactive with epoxy functionality. Suitable ester group-containingoligomers includes those described in U.S. Pat. No. 4,764,430, column 4,line 26 to column 5, line 68, which is hereby incorporated by reference.

Other useful crosslinking agents include acid-functional acryliccrosslinkers made by copolymerizing methacrylic acid and/or acrylic acidmonomers with other ethylenically unsaturated copolymerizable monomersas the polyacid crosslinking material. Alternatively, acid-functionalacrylics can be prepared from hydroxy-functional acrylics reacted withcyclic anhydrides.

In accordance with certain embodiments of the present invention, thecrosslinking agent (b) which typically is water soluble/dispersible, maybe present as a component in the film-forming composition in an amountranging from 0 to at least 10 weight percent, or at least 10 to at least20 weight percent, or from at least 20 to at least 30 weight percentbased on total resin solids weight in the film-forming composition. Inaccordance with certain embodiments of the present invention, thecrosslinking agent may be present as a component in the film-formingcomposition in an amount ranging from less than or equal to 70 to lessthan or equal to 60 weight percent, or less than or equal to 60 to lessthan or equal to 50 weight percent, or less than or equal to 50 to lessthan or equal to 40 weight percent based on total resin solids weight ofthe film-forming composition. The crosslinking agent can be present inthe film-forming composition in an amount ranging between anycombination of these values inclusive of the recited ranges

The film-forming composition can contain, in addition to the componentsdescribed above, a variety of other adjuvant materials such as thosedescribed below. If desired, other resinous materials can be utilized inconjunction with the previously described ingredients so long as theresultant coating composition is not detrimentally affected in terms ofapplication, physical performance and appearance properties.

The film-forming composition of the present invention can furtherinclude inorganic and/or inorganic-organic particles, for example,silica, alumina, including treated alumina (e.g. silica-treated aluminaknown as alpha aluminum oxide), silicon carbide, diamond dust, cubicboron nitride, and boron carbide.

In addition, in accordance with certain additional embodiments of thepresent invention, inorganic particles which may, for example, besubstantially colorless, such as silica, for example, colloidal silica,can be present. Such materials may provide enhanced mar and scratchresistance. Other suitable inorganic particles can include fumed silica,amorphous silica, alumina (i.e., aluminum oxide), colloidal alumina,titanium dioxide, zirconia, colloidal zirconia and mixtures thereof.Such particles can have an average particle size ranging from sub-micronsize (e.g., nanosized particles) up to 10 microns depending upon the enduse application of the composition and the desired effect.

In an embodiment of the invention, the particles comprise inorganicparticles that have an average particle size ranging from 1 to 10microns, or 1 to 5 microns prior to incorporation into the composition.In another embodiment of the present invention, the inorganic particlescomprise aluminum oxide having an average particle size ranging from 1to 5 microns prior to incorporation into the film-forming composition.

In a further embodiment of the invention, the inorganic particles havean average particle size of less than 50 microns prior to incorporationinto the composition. In another embodiment, the present invention isdirected to film-forming compositions as previously described whereinthe inorganic particles have an average particle size ranging from 1 toless than 1000 nanometers prior to incorporation into the composition.In another embodiment, the present invention is directed to film-formingcompositions as previously described wherein the inorganic particleshave an average particle size ranging from 1 to 100 nanometers prior toincorporation into the composition.

In another embodiment, the present invention is directed to film-formingcompositions as previously described wherein the inorganic particleshave an average particle size ranging from 5 to 50 nanometers prior toincorporation into the composition. In another embodiment, the presentinvention is directed to film-forming compositions as previouslydescribed wherein the inorganic particles have an average particle sizeranging from 5 to 25 nanometers prior to incorporation into thecomposition. The particle size may range between any combination ofthese values inclusive of the recited values. These materials mayconstitute, in certain embodiments of the present invention, up to 30percent by weight of the total weight of the film-forming composition.

In a further embodiment of the present invention, the particles, whichare typically inorganic particles, can be present in the composition inan amount ranging from 0.05 to 5.0 weight percent, or from 0.1 to 1.0weight percent, or from 0.1 to 0.5 weight percent based on total weightof the film-forming composition. The amount of particles present in thecomposition can range between any combination of these values inclusiveof the recited values.

The film-forming composition also can contain a catalyst to acceleratethe cure reaction, for example, between the blocked polyisocyanatecuring agent and the reactive hydroxyl groups of the aqueousdispersion(s) of polymeric microparticles. Examples of suitablecatalysts include organotin compounds such as dibutyl tin dilaurate,dibutyl tin oxide and dibutyl tin diacetate. Catalysts suitable forpromoting the cure reaction between an aminoplast curing agent and thereactive hydroxyl and/or carbamate functional groups of thethermosettable dispersion include acidic materials, for example, acidphosphates such as phenyl acid phosphate, and substituted orunsubstituted sulfonic acids such as dodecylbenzene sulfonic acid orparatoluene sulfonic acid. The catalyst usually is present in an amountranging from 0.1 to 5.0 percent by weight, or 0.5 to 1.5 percent byweight, based on the total weight of resin solids present in thefilm-forming composition

Other additive ingredients, for example, plasticizers, surfactants,thixotropic agents, anti-gassing agents, flow controllers,anti-oxidants, UV light absorbers and similar additives conventional inthe art can be included in the composition. These ingredients typicallyare present in an amount of up to about 40 percent by weight based onthe total weight of resin solids.

In certain embodiments of the present invention, the film-formingcomposition forms a generally continuous film at ambient temperature(approximately 23-28° C. at 1 atm pressure). A “generally continuousfilm” is formed upon coalescence of the applied coating composition toform a uniform coating upon the surface to be coated. By “coalescence”is meant the tendency of individual particles or droplets of the coatingcomposition, such as would result upon atomization of a liquid coatingwhen spray applied, to flow together thereby forming a continuous filmupon the substrate which is substantially free from voids or areas ofvery thin film thickness between the coating particles.

The film-forming compositions of the present invention also may, incertain embodiments, be formulated to include one or more pigments orfillers to provide color and/or optical effects, or opacity. Suchpigmented film-forming compositions may be suitable for use inmulti-component composite coatings as discussed below, for example, as aprimer coating or as pigmented base coating composition in acolor-plus-clear topcoat system, or as a monocoat topcoat. In anembodiment of the present inventions the film-forming composition is apigment-containing primer coating composition suitable for subsequentapplication of one or more of the previously mentioned topcoats.

The solids content of the film-forming composition generally ranges from20 to 75 weight percent, or 30 to 65 weight percent, or 40 to 55 weightpercent on a basis of total weight of the film-forming composition.

As aforementioned the present invention also is directed to multi-layercomposite coatings. The multi-layer composite coating of the presentinvention can comprise a base coat formed from a base-coat film-formingcomposition (typically a pigmented color coat), and a top coat formedfrom a top coat film-forming composition applied over the base coat(typically a transparent or clear coat). At least one of the basecoatfilm-forming composition and the topcoat film-forming compositioncomprises the film-forming composition of the present invention. Thefilm-forming composition of the base coat can be any of the compositionsuseful in coatings applications, including any of the previouslydescribed film-forming compositions in accordance with the presentinvention. The film-forming composition of the base coat comprises aresinous binder and, optionally, a pigment to act as the colorant.Particularly useful resinous binders are acrylic polymers, polyesters,including alkyds and polyurethanes such as those discussed in detailabove.

The resinous binders for the base coat can be organic solvent-basedmaterials such as those described in U.S. Pat. No. 4,220,679, notecolumn 2 line 24 continuing through column 4, line 40, which isincorporated herein by reference. Also, water-based coating compositionssuch as those described in U.S. Pat. No. 4,403,003, U.S. Pat. No.4,147,679 and U.S. Pat. No. 5,071,904 (incorporated herein by reference)can be used as the binder in the base coat composition.

The base coat composition can contain pigments as colorants as indicatedabove. Suitable metallic pigments include aluminum flake, copper orbronze flake and metal oxide coated mica. Besides the metallic pigments,the base coat compositions can contain non-metallic color pigmentsconventionally used in surface coatings including inorganic pigmentssuch as titanium dioxide, iron oxide, chromium oxide, lead chromate, andcarbon black; and organic pigments such as, e.g., phthalocyanine blueand phthalocyanine green.

Optional ingredients in the base coat composition include those whichare well known in the art of formulating surface coatings, such assurfactants, flow control agents, thixotropic agents, fillers,anti-gassing agents, organic co-solvents, catalysts, and other customaryauxiliaries. Examples of these materials and suitable amounts aredescribed in U.S. Pat. Nos. 4,220,679, 4,403,003, 4,147,769 and5,071,904, which are incorporated herein by reference.

The base coat compositions can be applied to the substrate by anyconventional coating technique such as brushing, spraying, dipping orflowing, but they are most often applied by spraying. The usual spraytechniques and equipment for air spraying, airless spray andelectrostatic spraying in either manual or automatic methods can beused.

During application of the base coat to the substrate, the film thicknessof the base coat formed on the substrate is typically 0.1 to 5 mils(about 2.54 to about 127 micrometers), or sometimes 0.1 to 2 mils (about2.54 to about 50.8 micrometers).

After forming a film of the base coat on the substrate, the base coatcan be cured or alternately given a drying step in which solvent isdriven out of the base coat film by heating or an air drying periodbefore application of the clear coat. Suitable drying conditions willdepend on the particular base coat composition, and on the ambienthumidity if the composition is water-borne, but often, a drying time offrom 1 to 15 minutes at a temperature of 75° to 200° F. (21° to 93° C.)will be adequate.

The solids content of the base coating composition generally ranges from15 to 60 weight percent, and sometimes 20 to 50 weight percent.

The topcoat (or clear coat if the transparent coating in acolor-plus-clear-system) composition is often applied to the base coatby spray application, however, the topcoat can be applied by anyconventional coating technique as described above. Any of the knownspraying techniques can be used such as compressed air spraying,electrostatic spraying and either manual or automatic methods. Asmentioned above, the topcoat can be applied to a cured or to a driedbase coat before the base coat has been cured. In the latter instance,the two coatings are then heated to cure both coating layerssimultaneously. Typical curing conditions range from 265° to 350° F.(129° to 175° C.) for 20 to 30 minutes. The clear coating thickness (dryfilm thickness) is typically 1 to 6 mils (about 25.4 to about 152.4micrometers).

During application of the top coating composition to the base coatedsubstrate, ambient relative humidity generally can range from about 30to about 80 percent, preferably about 50 percent to 70 percent.

In an alternative embodiment, after the base coat is applied (and cured,if desired), multiple layers of top coatings (e.g. clear coatings) canbe applied over the base coat. This is generally referred to as a“clear-on-clear” application. For example, one or more layers of aconventional transparent or clear coat can be applied over the base coatand one or more layers of transparent coating of the present inventionapplied thereon. Alternatively, one or more layers of a transparentcoating of the present invention can be applied over the base coat as anintermediate topcoat, and one or more conventional transparent coatingsapplied thereover.

The multi-layer composite coating compositions can be applied overvirtually any substrate including wood, metals, glass, cloth, plastic,foam, including elastomeric substrates and the like. They areparticularly useful in applications over metals and elastomericsubstrates that are utilized in the manufacture of motor vehicles. Thesubstantially organic solvent-free film-forming compositions of thepresent invention provide multi-component composite coating systems thathave appearance and performance properties commensurate with thoseprovided by solvent-based counterparts with appreciably less volatileorganic emissions during application.

Illustrating the invention are the following examples, which, however,are not to be considered as limiting the invention to their details.Unless otherwise indicated, all parts and percentages in the followingexamples, as well as throughout the specification, are by weight.

EXAMPLES

The following Examples A and B describe the preparation of resinousbinders for use in the preparation of film-forming compositions of thepresent invention. Example C describes the preparation ofwater-dilutable additive materials for use in compositions of thepresent invention. Example D describes the preparation of a functionalpolysiloxane additive for use in compositions of the present invention.Example E describes the preparation of aqueous dispersions of polymericmicroparticles prepared by emulsion polymerization for use in thepreparation of compositions of the present invention. Examples F and Gdescribes the preparation of film-forming compositions of the presentinvention that include materials prepared in Examples A, C and D.Example H describes the preparation of film-forming compositions of thepresent invention that include materials prepared in Examples B, C, D,and E.

Example A Resinous Binder A

A resinous binder was prepared as described below from the ingredientsof Table 1. The amounts listed are the total parts by weight in gramsand the amount within parenthesis are total parts by weight based onsolids, in grams.

TABLE 1 Ingredient Amount Charge 1 Acrylic¹ 2316.2 (1466.2) TRIXENEDP9B/1504² 299.2 (209.5) MIBK³ 53.7 (0)   Charge 2 TINUVIN 400⁴ 73.9(62.8) TINUVIN 123⁵ 20.9 (20.9) BYK-390⁶ 20.9 (10.5) Polybutylacrylate⁷10.5 (6.3)  Dibutyltin Dilaurate 4.8 (4.8) Dimethyl Ethanolamine 26.3(0)   SURFYNOL 2502⁸ 14.7 (14.7) Charge 3 MIBK 53.7 (0)   Charge 4Dimethyl Ethanolamine 6.6 (0)   Deionized Water 3022.0 (0)    Charge 5Deionized Water 100.0 (0)    Charge 6 FOAM KILL 649⁹ 1.7 (1.7) ¹Acrylicresin (30.3% styrene, 19.9% hydroxyethyl methacrylate, 28.7% CARDURA E(glycidyl neodecanoate available from Shell Chemical Co.), 11.0% acrylicacid, and 10.15% 2-ethylhexyl acrylate). ²Blocked isocyanate availablefrom Baxenden Chemical Ltd., Lancashire, England. ³Methyl isobutylketone. ⁴Light stabilizer available from Ciba Specialty Chemicals,Basel, Switzerland. ⁵Light stabilizer available from Ciba SpecialtyChemicals, Basel, Switzerland. ⁶Acrylate leveling additive availablefrom BYK-Chemie USA Inc., Wallingford, Connecticut ⁷60% solids instyrene. ⁸Surfactant available from Air Products and Chemicals, Inc.,Allentown, Pennsylvania. ⁹Defoamer available from Crucible Chemical.

Charge 1 and then charge 2 were added to a flask at ambient conditionsand mixed until homogeneous. The temperature was increased to 25° C. Atthat temperature, the mixture was added to a flask containing charge 4,by dripping the mixture into the flask over one hour. Charge 3 was thenadded to the flask and the contents were held for 30 minutes. Theresulting pre-emulsion was passed once through a Microfluidizer® M110T(available from Microfluidics Corp., Newton, Mass.) at 11,500 psi withcooling water to maintain the pre-emulsion at approximately roomtemperature. Charge 5 was then passed through the Microfluidizer torinse. Solvents were removed by vacuum distillation. The finalcomposition contained about 46 weight % solids with Charge 6 being addedas needed during vacuum distillation.

Example B Resinous Binder B

A resinous binder was prepared as described below from the ingredientsof Table 2. The amounts listed are the total parts by weight in gramsand the amount within parenthesis are total parts by weight based onsolids, in grams.

TABLE 2 Ingredient Amount Charge 1 Acrylic¹⁰ 2182.8 (1382.4)Crosslinker¹¹ 145.7 (126.8) Flex Acrylic¹² 330.0 (250.8) MIBK 47.3 (0)  Charge 2 TINUVIN 400 54.7 (46.5) TINUVIN 123 18.6 (18.6) BYK-337¹³ 0.4(0.1) DiMethyl Ethanolamine 36.7 (0)   Dimethyl Ethanolamine 5.4 (0)  SURFYNOL 2502 13.8 (13.8) Charge 3 MIBK 47.3 (0)   Charge 4 DimethylEthanolamine 9.2 (0)   Deionized Water 3151.0 (0)    Charge 5 DeionizedWater 88.0 (0)   Charge 6 FOAM KILL 649⁹ 1.5 (1.5) ¹⁰Acrylic resin(28.67% styrene, 19.9% hydroxyethyl methacrylate, 28.6% CARDURA E(glycidyl neodecanoate available from Shell Chemical Co.), 12.75%acrylic acid, and 10.15% 2-ethylhexyl acrylate). ¹¹Blocked isocyanate(87% solids in MIBK) produced by charging 1930.0 parts by weightDESMODUR N3300 (a trimer of hexamethylene diisocyanate available fromBayer Corporation) to a reactor containing 1.75 parts by weightdibutyltin dilaurate and 436.8 parts by weight MIBK. 540.7 parts byweight of benzyl alcohol was then added over 90 minutes keeping thetemperature below 80° C. After completion of this addition, the reactiontemperature was maintained at 80° C. and monitored by infraredspectroscopy for disappearance of the isocyanate band. ¹²Acrylic resin(31.4% CARDURA E (glycidyl neodecanoate available from Shell ChemicalCo.), 5.5% isostearic acid, 12.2% methyl methacrylate, 10.3% styrene,17.1% 2-ethylhexyl acrylate, 12.9% hydroxyethyl acrylate, 10.6% acrylicacid). ¹³Solution of a polyether modified poly-dimethyl-siloxaneavailable from BYK-Chemie USA Inc., Wallingford, Connecticut.

Charge 1 and then charge 2 were added to a flask at ambient conditionsand mixed until homogeneous. The temperature was increased to 25° C. Atthat temperature, the mixture was added to a flask containing charge 4,by dripping the mixture into the flask over one hour. Charge 3 was thenadded to the flask and the contents were held for 30 minutes. Theresulting pre-emulsion was passed once through a Microfluidizer® M110T(available from Microfluidics Corp., Newton, Mass.) at 11,500 psi withcooling water to maintain the pre-emulsion at approximately roomtemperature. Charge 5 was then passed through the Microfluidizer torinse. Solvents were removed by vacuum distillation. The finalcomposition contained about 46 weight % solids with Charge 6 being addedas needed during vacuum distillation.

Example C Water Dilutable Additive C

Table 3 sets forth the components and amounts for various waterdilutable additives C1 through C12 that were prepared as describedbelow.

TABLE 3 Methoxypoly- Polyethylene Example Isocyanate Isocyanateethyelene Glycol No. Type Equivalents Glycol Type Equivalents C1 IPDI¹⁴1.0 MPEG 2000²⁰ 1.004 C2 IPDI 1.0 MPEG 750²¹ 1.004 C3 IPDI 1.0 MPEG550²² 1.004 C4 IPDI 1.0 MPEG 350²³ 1.004 C5 TDI¹⁵ 1.0 MPEG 2000 1.004 C6m-TMXDI¹⁶ 1.0 MPEG 2000 1.004 C7 HDI¹⁷ 1.0 MPEG 2000 1.004 C8 HDITrimer¹⁸ 1.0 MPEG 2000 1.004 C9 IPDI Trimer¹⁹ 1.0 MPEG 2000 1.004 C10IPDI 1.0 MPEG 2000/ 0.502/0.502 MPEG 750 C11 IPDI 1.0 MPEG 2000/0.502/0.502 MPEG 550 C12 IPDI 1.0 MPEG 2000/ 0.502/0.502 MPEG 350¹⁴Isophorone Diisocyanate. ¹⁵Toluene Diisocyanate.¹⁶META-Tetramethylxylylene Diisocyanate commercially available fromCYTEC Industries, Inc. ¹⁷Hexamethylene Diisocyanate. ¹⁸DEMODUR 3390commercially available from Bayer Corporation. ¹⁹T-1890L commerciallyavailable from DeGussa Corporation. ²⁰CARBOWAX MPEG 2000 commerciallyavailable from The Dow Chemical Company. ²¹CARBOWAX MPEG 750commercially available from The Dow Chemical Company. ²²CARBOWAX MPEG550 commercially available from The Dow Chemical Company. ²³CARBOWAXMPEG 350 commercially available from The Dow Chemical Company.

In each case, the isocyanate, the polyethylene glycol, and methylisobutyl ketone were charged to a glass reactor equipped with anagitator, condenser, thermocouple, and nitrogen blanket. The charge washeated to a temperature 55° C. After complete dissolution of the charge,a charge of dibutyl tin dilaurate was added (0.05% by weight based onthe total weight of the reactants). The reactants were then slowlyheated over a one-half hour period to about 90° C. The reactants werecooled as necessary to 85-90° C. The reaction was monitored by infraredspectroscopy for disappearance of the isocyanate peak. Deionized waterwas then added to the reactor over a 20 minute period to give adispersion solids of about 64.5%. The dispersions were held for one hourat about 70-75° C. under agitation. The product was then distilled toremove methyl isobutyl ketone and provide a final dispersion solid ofabout 40-45%.

Example D Water Dilutable Additive D

A reactive functional group-containing polysiloxane was prepared from apolysiloxane polyol that was prepared as described below from themixture of ingredients of Table 4.

TABLE 4 Equivalent Parts By Weight Ingredients Weight² Equivalents(kilograms) Charge I: Trimethylolpropane 174.0 756.0 131.54 monoallylether Charge II: MASILWAX BASE²⁴ 156.7²⁵ 594.8 93.21 Charge III:Chloroplatinic acid 10 ppm Toluene 0.23 Isopropanol 0.07²⁴Polysiloxane-containing silicon hydride, commercially available fromLubrizol Corporation. ²⁵Equivalent weight based on mercuric bichloridedetermination.

To a suitable reaction vessel equipped with a means for maintaining anitrogen blanket, Charge I and an amount of sodium bicarbonateequivalent to 20 to 25 ppm of total monomer solids were added at ambientconditions, and the temperature was gradually increased to 75° C. undera nitrogen blanket. At that temperature, about 5.0% of Charge II wasadded under agitation, followed by the addition of Charge III,equivalent to 10 ppm of active platinum based on total monomer solids.The reaction was then allowed to exotherm to 95° C. at which time theremainder of Charge II was added at a rate such that the temperature didnot exceed 95° C. After completion of this addition, the reactiontemperature was maintained at 95° C. and monitored by infraredspectroscopy for disappearance of the silicon hydride absorption band(Si—H, 2150 cm⁻¹).

To produce the reactive functional group-containing polysiloxane, 360.3grams of the polysiloxane polyol described above was added to a reactionflask. The polyol was then heated to 60° C. and 84.4 g ofm-hexahydrophthalic anhydride was added over 30 minutes. The reactionwas held for 3 hours and checked for complete reaction by IR(disappearance of peak at 1790). The reaction was then cooled to ambienttemperature and 44.7 g of dimethyl ethanolamine was added over 30minutes. The reaction was held at ambient temperature for 15 minutes and383.6 g of deionized water added over 3 hours.

Example E Additive E Aqueous Dispersions of Polymeric Microparticles

The aqueous dispersions of polymeric microparticles of Examples E1 to E9prepared by emulsion polymerization were prepared as described belowfrom a mixture of the following ingredients in a glass reactor equippedwith an agitator, a nitrogen blanket, a monomer feed zone, and athermocouple.

CHARGE 1 Deionized Water AEROSOL OT75²⁶ 0.15% active weight percentbased on monomer charge Sodium Bicarbonate 0.125% by weight based onmonomer charge CHARGE 2 Ammonium Persulfate 0.4% by weight based onmonomer charge Water ²⁶A 75% solution of dioctylsodium sulfosuccinate inisoproponal available from CYTEC Industries, Inc.Charge 3

Pre-emulsions (weight ratio of monomer to water of 55:45) were preparedfrom the monomers listed in Table 5 (weight percent based on 100 partsmonomer) using 0.5% Aerosol OT75 by active weight based on the monomercharge. The pre-emulsions were prepared by mixing the monomers with thewater and surfactant for 30 minutes.

TABLE 5 Example Monomer No. Styrene MMA²⁷ BA²⁸ AA²⁹ NMA³⁰ HEMA³¹ PS³² pH% Gel³³ E1 44.75 44 0 8.5 2 2.5 1480 8.8 88 E2 89.5 0 0 8.5 2 0 15007.83 98 E3 45 44.5 0 8.5 2 0 1500 8.85 88 E4 22.38 67.12 0 8.5 2 0 13508.62 71 E5 53.25 44.75 0 2 0 0 1300 9.03 2 E6 44.75 42.25 0 8.5 2 2.5  940⁸ 8.7 — E7 44.75 0 42.25 8.5 2 0 1800 7.15 98 E8 53.25 0 44.75 2 20 1800 9.75 — E9 90.75 0 0 8.5 1.25 0 1600 8.6 96  E10 44.45 42.25 0 8.52.0 2.8 1455 9.43 98.3 ²⁷Methyl Methacrylate. ²⁸Butyl Methacrylate.²⁹Acrylic Acid. ³⁰A 50% solution of N-Methylolacrylamide in wateravailable from Cytec Industries, Inc. ³¹Hydroxy Ethyl Methacrylate.³²Average particle size measured by photon correlation spectroscopyusing a Malvern Zetasizer 3000Hsa. ³³As measured by digestion of dryparticles in acetone. ³⁴The amount of surfactant was tripled to reduceparticle size.

Charge 1 was heated to about 80° C. under a blanket of nitrogen. Charge2 then was added at this temperature and held for five minutes. Charge 3was added over a three-hour period followed by a one-hour hold. Thereaction was allowed to cool to less than 50° C. and a portion ofdimethyl amino ethanol in water (50:50 ratio) was added to increase thepH to about 7.0. The respective polymers each had a solid content ofabout 32%.

Example F1 Film-Forming Compositions Containing Materials from ExamplesA, C and D

Film-forming compositions were prepared as described below from thecomponents listed in Table 6. Seven film-forming compositions wereprepared for Example F1 by varying the Example C additive as reflectedin Table 7.

TABLE 6 Component No. Description Amount (grams) 1 Resinous Binder ofExample A 183.5 2 Polysiloxane of Example D 2.13 3 TEXANOL³⁵ 9.0 4 ButylAcetate³⁶ 3.0 5 Deionized water 29.00 6 Additives of Example C 12.5 7CYMEL 327³⁷ 12.8 8 CYMEL 303³⁸ 3.0 9 Premix 1 CYMEL 327 5.3 AEROSIL200³⁹ 0.2 10 Premix 2 Dodecylbenzylsulfonic Acid 0.2Dimethylethanolamine (50% in 0.182 deionized water)⁴⁰ Deionized water0.160 11 Premix 3 BORCHI Gel LW44⁴¹ 0.24 Deionized Water 0.96 ³⁵2,2,4Trimmethyl-1,3 Pentanediol Monoisobuterate available from Dow ChemicalCompany. ³⁶N-Butyl Acetate available from Dow Chemical Company. ³⁷HighImino Melamine-Formaldehyde Crosslinking Agent available from CytecIndustries, Inc. ³⁸Hexamethoxymethyl melamine resin available from CytecIndustries, Inc. ³⁹Silica commercially available from DegussaCorporation. ⁴⁰Available from PPG Industries, Inc. ⁴¹Non-ionic,polyurethane based thickener available from Borchers GmbH.

Premix 1 was prepared by adding the Areosil 200 to the Cymel 327 andstirring. The mixture was added to an EIGER mill to achieve a grindfineness of 7+Hegman. Premix 2 was prepared slowly agitatingdodecylbenzylsulfonic acid and adding demethylehtanolamine (50% indeionized water) and deionized water. Premix 3 was prepared by stirringthe Borchi Gel LW44 and adding deionized water until a uniformconsistency was achieved.

The film-forming composition was prepared by charging component 1 andthen adding component 2 under agitation until fully incorporated. Then,under moderate agitation, components 3 to 11 were added. The finalcompositions had a solids content of 45% and a viscosity of 30 secondsusing a #4 Din cup.

Test Substrates

The test substrates were ACT cold roll steel panels (4″×12″) supplied byACT Laboratories, Inc. and were electrocoated with a cationicelectrodepositable primer commercially available from PPG Industries,Inc. as ED-6060. The panels were then spray coated in two coats with EWBReflex Silver Basecoat commercially available from PPG Industries, Inc.to film thicknesses ranging from 0.4 to 0.6 mils. The basecoat wasflashed for 5 minutes at ambient temperature and then baked for 5minutes at 176° F. (80° C.). The substrate was then cooled to ambienttemperature. After cooling, film-forming compositions of Example F1 werespray applied, with a target film thickness of 1.3 to 1.7 mils, in twocoats without flash time between coats. The substrates coated with theExample F1 compositions were flashed for 2 minutes at ambienttemperature and then the coated substrates were placed in an oven at150° C., prior to increasing the oven temperature to 311° C. The coatedsubstrates were cured for 23 minutes in an oven set at 311° C.Appearance and properties for the coatings are reported below in Table7.

TABLE 7 Water Dilutable Coating Additive C % 20° Gloss Retained ExampleNo. Example No. Gloss⁴² Haze⁴² DOI⁴³ LW⁴⁴ SW⁴⁴ after scratch testing⁴⁵F1a C1 100 345 76 4 14 56 F1b C4 99 331 78 4 15 40 F1c  C10 99 322 81 315 41 F1d  C12 99 350 75 8 14 46 F1e C3 99 339 81 4 17 44 F1f  C11 100350 77 4 13 46 F1g C2 99 330 83 3 15 43 ⁴²Gloss and haze of test panelscoated as described above was determined at a 20° angle using aMicro-TriGloss Reflectometer available from BYK Gardner, Inc.⁴³Distinctness of image (“DOI”) of sample panels was determined using aDorigon II DOI Meter, which is commercially available from Hunter Lab,where a higher value indicates better coating appearance on the testpanel. ⁴⁴Smoothness of the coated test panels was measured using a BykWavescan in which results are reported as long wave and short wavenumbers where lower values mean smoother films. ⁴⁵Coated panels weresubjected to scratch testing by linearly scratching the coated surfacewith a weighted abrasive paper for ten double rubs using an Atlas AATCCScratch Tester, Model CM-5, available from Atlas Electrical DevicesCompany of Chicago, Illinois. The abrasive paper used was 3M 281QWETORDRY ™ PRODUCTION ™ 9 micron polishing paper sheets, which arecommercially available from 3M Company of St. Paul, Minnesota. Panelswere then rinsed with tap water and carefully patted dry with a papertowel. The 20° gloss was measured (using the same gloss meter as thatused for the initial 20° gloss) on the scratched area of each testpanel. Using the lowest 20° gloss reading from the scratched area, thescratch results are reported as the percent of the initial glossretained after scratch testing using the following calculation: 100% *(scratched)/(initial gloss). Higher values for percent of gloss retainedare desirable.

Example F2 Film-Forming Compositions Containing Materials from ExamplesA, C and D

Film-forming compositions were prepared as described below from thecomponents listed in Table 8. The compositions were prepared in the samemanner as the compositions of Example F1 described above. Sevenfilm-forming compositions were prepared for Example F2 by varying theExample C additive as reflected in Table 9.

TABLE 8 Component No. Description Amount (grams) 1 Resinous Binder ofExample A 183.5 2 Polysiloxane of Example D 2.13 3 TEXANOL 9.0 4 ButylAcetate 3.0 5 Deionized water 29.00 6 Additives of Example C 7.7 7 CYMEL327 12.8 8 CYMEL 303 3.0 9 Premix 1 CYMEL 327 5.3 AEROSIL 200 0.2 10Premix 2 Dodecylbenzylsulfonic Acid 0.2 Dimethylethanolamine (50% in0.182 deionized water) Deionized water 0.160 11 Premix 3 BORCHI Gel LW440.24 Deionized Water 0.96

Test Substrates

The test substrates were prepared in the same manner as is described inExample F1 above. Appearance and properties for the coatings of ExampleF2 are reported below in Table 9. These properties were measured by thesame methods as described above for the coatings of Example F1.

TABLE 9 Water Dilutable Coating Additive C % 20° Gloss Retained ExampleNo. Example No. Gloss Haze DOI LW SW after scratch testing F2a C1 100337 80 3 17 56 F2b C4 96 335 71 6 16 48 F2c  C10 99 347 74 5 15 50 F2d C12 99 343 72 5 15 49 F2e C3 99 340 78 4 15 39 F2f  C11 99 341 75 4 1554 F2g C2 99 344 73 5 15 43

Example G Compositions Containing Materials from Examples A, C1 and D

Film-forming compositions were prepared as described below from thecomponents listed in the following Table 10.

TABLE 10 Amount (grams) Component Example Example Example Example No.Description G1 G2 G3 G4 1 Resinous Binder of Example A 174.6 174.6 174.6174.6 2 Byk 345⁴⁶ 0.48 0.48 0.48 0.48 3 Byk 325⁴⁷ 0.24 0.24 0.24 0.24 4Polysiloxane of Example D 4.25 4.25 4.25 4.25 5 TEXANOL 10.0 10.0 10.010.0 6 Isobutanol 6.0 6.0 6.0 6.0 7 Isosteryl Alcohol 4.0 4.0 4.0 4.0 8Deionized water 15.0 15.0 15.0 15.0   9a Additive of Example C1 0 2.56.3 10.5  9b CYMEL 303 3.1 0 0 0 10  Premix 1 CYMEL 327 19.88 23.5 23.523.5 AEROSIL 200 0.4 0.4 0.4 0.4 11  Premix 2 Dodecylbenzylsulfonic Acid0.196 0.196 0.196 0.196 Dimethylethanolamine (50% in 0.167 0.167 0.1670.167 deionized water) Deionized water 0.167 0.167 0.167 0.167 12 Premix 3 BORCHI Gel LW44 0.214 0.4 0.4 0.374 Deionized Water 0.856 1.61.6 1.496 ⁴⁶Available from Byk-Chemie, Wallingford, CT. ⁴⁷Available fromByk-Chemie, Wallingford, CT.

Premix 1 was prepared by adding the Areosil 200 to the Cymel 327 andstirring. The mixture was added to an EIGER mill to achieve a grindfineness of 7+Hegman. Premix 2 was prepared slowly agitatingdodecylbenzylsulfonic acid and adding demethylehtanolamine (50% indeionized water) and deionized water. Premix 3 was prepared by stirringthe Borchi Gel LW44 and adding deionized water until a uniformconsistency was achieved.

The film-forming composition was prepared by charging components 1through 3 and then adding component 4 under agitation until fullyincorporated. Then, under moderate agitation, components 5 to 12 wereadded. The final compositions had a solids content of 45% and aviscosity of about 30 seconds using a #4 Din cup.

Test Substrates

The test substrates were ACT cold roll steel panels (4″×12″) supplied byACT Laboratories, Inc. and were electrocoated with a cationicelectrodepositable primer commercially available from PPG Industries,Inc. as ED-6060. The panels were then spray coated in two coats with EWBObsidian Schwartz Basecoat commercially available from PPG Industries,Inc. to film thicknesses ranging from 0.4 to 0.6 mils. The basecoat wasflashed for 5 minutes at ambient temperature and then baked for 5minutes at 176° F. (80° C.). The substrate was then cooled to ambienttemperature. After cooling, film-forming compositions of Example G1-G4were spray applied, with a target film thickness of 1.3 to 1.7 mils, intwo coats without flash time between coats. The substrates coated withthe Example G compositions were flashed for 2 minutes at ambienttemperature and then the substrates were placed in an oven at 150° C.,prior to increasing the oven temperature to 311° C. The coatedsubstrates were cured for 23 minutes in an oven set at 311° C.Appearance and properties for the coatings of Example G are reportedbelow in Table 11.

TABLE 11 Coating % 20° Gloss Retained Pop Resistance Example No. GlossHaze DOI LW SW after scratch testing microns pop⁴⁸ G1 93 17 87 7.4 15.824 35 G2 93 21 92 9.7 18.5 24 40 G3 93 90 20 9.1 16.7 31 42 G4 92 24 927.2 17.2 24 45 ⁴⁸Pop resistance (measures the ability of the coating toresist the release of air from the coating composition as it is cured)was evaluated visually by examining the panels for pops and noting thefilm thickness at which the popping begins. This is done by visuallyviewing the panel and determining the lowest film build withoutsignificant popping for panels coated with increasing film thicknessalong the distance from the top of the panel which had the lowest filmbuild. A higher value indicates better resistance to popping.

Example H Compositions Containing Materials from Examples B, C, D and E

Film-forming compositions were prepared as described below from thecomponents listed in the following Table 12.

TABLE 12 Component No. Description Amount (grams) 1 Resinous Binder ofExample B 142.25 2 Microparticles of Example E 4.75 3 Polysiloxane fromExample D 2.13 4 TEXANOL 10.0 5 Isostearyl Alcohol⁴⁶ 4.0 6 Deionizedwater 29.00 7 Additive from Example C1 12.5 8 CYMEL 303 3.0 9 Premix 1RESIMENE 741⁴⁷ 12.0 AEROSIL 200 0.24 10 Premix 2 DodecylbenzylsulfonicAcid 0.2 Dimethylethanolamine (50% in 0.182 deionized water) Deionizedwater 0.160 11 Premix 3 BORCHI Gel LW44 0.24 Deionized Water 0.96⁴⁶Available from Goldschmidt Chemical Corp., Hopewell, Virginia.⁴⁷Methoxymethyl melamine resin available from Cytec Industries, Inc.

Premix 1 was prepared by adding the AEROSIL 200 to the RESIMENE 741 andstirring. The mixture was added to an EIGER mill to achieve a grindfineness of 7+Hegman. Premix 2 was prepared slowly agitatingdodecylbenzylsulfonic acid and adding demethylehtanolamine (50% indeionized water) and deionized water. Premix 3 was prepared by stirringthe Borchi Gel LW44 and adding deionized water until a uniformconsistency is achieved.

The film-forming composition was prepared by blending components 1 and 2and then adding component 3 under agitation until fully incorporated.Then, under moderate agitation, components 3 to 11 are added. The finalcompositions had a solids content of 45% and a viscosity of 30 secondsusing a #4 Din cup.

Test Substrates

The test substrates were prepared in the same manner as is described inExample F1. Appearance and properties for the coatings of Example G arereported below in Table 13. The gloss, haze, DOI, and LW/SW smoothnesswere measured by the same methods as described for the coatings ofExample F1.

TABLE 13 Pop Coating resistance Pop for Example Additive E micronscontrol No. Example No. Gloss Haze DOI LW SW pop⁴⁸ each set Control None95 17 96 4.8 19.2 40 G1 E1 94 14 97 1.6 7.0 50 45 G2 E2 94 17 94 6.312.2 100 40 G3 E3 96 16 90 19.3 17.9 45 40 G4 E4 96 17 89 17.7 20.3 4840 G5 E5 94 14 97 1.6 8 45 45 G6 E6 95 15 95 6.2 17.5 38 41 (withcontrol MG 45) G7 E9 95 15 96 4 22.8 47 45

Example I

This example describes the preparation of three water-based pigmentedprimer coating compositions. The primer coating compositions of ExamplesI-2 and I-3 contain the aqueous dispersion of polymeric microparticlesof Example E10 in accordance with the present invention, while thecomposition of Comparative Example I-1 contains none. The respectiveprimer coating compositions were prepared as described below from amixture of the following ingredients.

Example I-1 Ingredients (Comparative) Example I-2 Example I-3 RESYDROLAX906W¹ 32.1 32.1 32.1 Dimethyl ethanolamine 0.09 0.09 0.09 Deionizedwater 2.7 2.7 2.7 SURFYNOL 104E² 0.17 0.17 0.17 Titanium dioxide 34.7734.77 34.77 Polyurethane aqueous 10.6 10.6 10.6 dispersion³ DAOTANVTW-1225⁴ 10.3 10.3 10.3 RESIMENE 745⁵ 8.3 8.3 8.3 Mineral spirits 0.60.6 0.6 Dimethyl ethanolamine 0.37 0.37 0.37 Dispersion of polymeric 01.7 3.4 microparticles of Example E10 ¹Resinous binder available fromUCB-Surface Specialties. ²Wetting agent available from Air Products andChemicals, Inc. ³High molecular weight polyurethane-polyester preparedas follows:. (i) an isocyanate prepolymer was first prepared as follows:a reaction vessel equipped with stirrer, thermocouple, condenser andnitrogen inlet was charged with 1362.0 g TERATHANE ® 2000, 280.4 g ofthe product of Example 2, 91.2 g dimethylolpropionic acid, 605.6 gisophorone diisocyanate, 580.0 g methyl ethyl ketone and heated to 60°C.; then 2.72 g dibutyltin dilaurate was added and the reactionexothermed to 78° C.; the reaction temperature was raised to 80° C. andthe contents were stirred until the isocyanate equivalent weight was1286; hen 71.5 g dimethylolpropionic acid was added to the reactionflask and the contents were stirred until the isocyanate equivalentweight was 1882.6. (ii) the prepolymer was dispersed then excess organicsolvent was removed via vacuum distillation as follows: 1392.0 g of theabove prepolymer was added over 19 minutes to a solution of 2028.1 gdeionized water, 61.8 g adipic acid dihydrazide and 50.4 g dimethylethanol amine stirring at 25° C. and at 510 rpm in a cylindrical gallonreaction flask equipped with baffles, double pitched bladed stirrer,thermocouple and condenser, the dispersion temperature after thisaddition was 41° C.; the reaction contents were stirred until noevidence of isocyanate was observed by FTIR; the dispersion wastransferred to a flask equipped with a stirrer, thermocouple, condenserand a receiver, and heated to 60° C. during which time methyl ethylketone and water were removed by vacuum distillation. The finaldispersion had a solids content of 39.81 weight percent (measured forone hour at 110° C.), a Brookfield viscosity of 240 centipoise using a#3 spindle at 60 rpm, an acid content of 0.203 meq acid/g, a casecontent of 0.200 meq base/g, a pH of 7.64 and a weight average molecularweight of 49148 in DMF. ⁴Polyurethane dispersion available fromUCT-Surface Specialties ⁵Melamine curing agent available from Solutia.

Each of the primer coating compositions of Examples I-1 through I-3above were prepared by mixing sequentially under mild agitation theingredients listed above. The viscosity of each of the primercompositions was adjusted using deionized water to 45 seconds using a #4Ford Cup at ambient temperature.

Sag Resistance Testing Procedure:

4″×12″ steel panels coated with ED 6060 cationic electrocoat (availablefrom PPG Industries, Inc.) (prepared test panels available from ACTLaboratories, Inc.) were used for sag resistance testing. Five holes (10millimeter diameter each) were punched equidistance apart down thelength of each test panel. For application of each composition, a testpanel was positioned vertically with the holes running from left toright. Each of the respective primer compositions of Examples I-1through I-3 were spray applied in two coats to the test panel usingautomated spray equipment at 75% relative humidity at 75° F. (23.9° C.)using 230 cc of the composition in each pass to create a film thicknesswedge (i.e., film thickness increasing from left to right of the testpanel). Each of the coated test panels was then allowed to “flash” at75% relative humidity/75° F. (23.9° C.), then heated for 25 minutes at atemperature of 285° F. (140.6° C.). Sag resistance was measured byrecording the length (millimeters) of the “sag”, i.e., the coating thatran from the bottom of the hole at a given dry film thickness. Forpurposes of the present invention, the sag was measured at a dry filmthickness of 45 microns. The sag resistance test results are set forthin Table 14 below:

TABLE 14 Sag Resistance Test Comparative Example I-1 Example I-2 ExampleI-3 Mm of sag 20 mm/45μ 2 mm/45μ 0 mm/45μ

The data presented in Table 14 above illustrate that the primer coatingcompositions containing the aqueous dispersion of polymericmicroparticles of Example E10 in accordance with the present inventionshow a significant improvement in sag resistance over an analogouscomposition which does not contain the aqueous dispersion of polymericmicroparticles.

It will be readily appreciated by those skilled in the art thatmodifications may be made to the invention without departing from theconcepts disclosed in the foregoing description. Such modifications areto be considered as included within the following claims unless theclaims, by their language, expressly state otherwise. Accordingly, theembodiments described in detail herein are illustrative only and are notlimiting to the scope of the invention which is to be given the fullbreadth of the appended claims and any and all equivalents thereof.

1. A multi-layer composite coating comprising a basecoat deposited fromat least one basecoat film-forming composition and a topcoat compositionapplied over at least a portion of the base coat in which the topcoat isdeposited from at least one topcoat film forming composition that issubstantially free of organic solvent, the topcoat film-formingcomposition comprising: an aqueous dispersion of polymericmicroparticles prepared by emulsion polymerization of a monomericcomposition comprising: (1) at least 10 percent by weight of one or morevinyl aromatic compounds; (2) 0.1 to 10 percent by weight of one or morecarboxylic acid functional polymerizable, ethylenically unsaturatedmonomers; (3) 0 to 10 percent by weight of one or more polymerizablemonomers having one or more functional groups which are capable ofreacting to form crosslinks; and (4) one or more polymerizable,ethylenically unsaturated monomers, where the weight percentages arebased on total weight of monomers present in the monomeric composition;wherein each of (1), (2), (3) and (4) are different one from the otherand wherein at least one of (3) and (4) is present in the monomericcomposition; and wherein the topcoat film-forming composition comprisesa material comprising a reactive-functional group-containingpolysiloxane; and wherein the material comprising thereactive-functional group-containing polysiloxane is different from themicroparticles of the aqueous dispersion.
 2. The multi-layer compositecoating of claim 1, wherein the base coat film-forming compositioncomprises one or more pigments.
 3. The multi-layer composite coating ofclaim 1, wherein the topcoat film-forming composition is substantiallyfree of pigments.
 4. The multi-layer composite coating of claim 1,wherein the topcoat film-forming composition further comprises inorganicparticles selected from fumed silica, amorphous silica, alumina,colloidal alumina, titanium dioxide, zirconia, colloidal zirconia, andmixtures thereof.
 5. The multi-layer composite coating of claim 4,wherein the inorganic particles have an average particle size rangingfrom 1 to 1000 nanometers prior to incorporation into the topcoatfilm-forming composition.
 6. The multi-layer composite coating of claim4, wherein the inorganic particles have an average particle size rangingfrom 1 to 10 microns prior to incorporation into the topcoatfilm-forming composition.
 7. The multi-layer composite coating of claim1, wherein the one or more vinyl aromatic compounds (1) comprises acompound selected from the group consisting of styrene, alpha-methylstyrene, vinyl toluene, para-hydroxy styrene and mixtures thereof. 8.The multi-layer composite coating of claim 1, wherein the one or morevinyl aromatic compounds is present in the monomeric composition in anamount ranging from 10 to 98 percent by weight based on total weight ofmonomers present in the monomeric composition.
 9. The multi-layercomposite coating of claim 8, wherein the one or more vinyl aromaticcompounds is present in the monomeric composition in an amount rangingfrom 20 to 80 percent by weight based on total weight of monomerspresent in the monomeric composition.
 10. The multi-layer compositecoating of claim 1, wherein the one or more carboxylic acid functionalpolymerizable, ethylenically unsaturated monomers (2) comprises amonomer selected from the group consisting of acrylic acid, methacrylicacid, itaconic acid, fumaric acid, maleic acid, anhydrides thereof, andmixtures thereof.
 11. The multi-layer composite coating of claim 1,wherein the one or more carboxylic acid functional polymerizable,ethylenically unsaturated monomers (2) is present in the monomericcomposition in an amount ranging from 0.5 to 8 percent by weight basedon total weight of monomers present in the monomeric composition. 12.The multi-layer composite coating of claim 11, wherein the one or morecarboxylic acid functional polymerizable, ethylenically unsaturatedmonomers (2) is present in the monomeric composition in an amountranging from 1 to 5 percent by weight based on total weight of monomerspresent in the monomeric composition.
 13. The multi-layer compositecoating of claim 1, wherein the one or more polymerizable monomershaving functional groups which are capable of reacting to formcrosslinks after polymerization (3) comprise functional groups selectedfrom amide groups, hydroxyl groups, amino groups, epoxy groups, thiolgroups, isocyanate groups, carbamate groups, and mixtures thereof. 14.The multi-layer composite coating of claim 1, wherein the one or morepolymerizable monomers having functional groups which are capable ofreacting to form crosslinking (3) comprise a compound selected fromγ-(meth)acryloxytrialkoxysilane, N-methylol(meth)acrylamide,N-butoxymethyl(meth)acrylamide, (meth)acryliclactones, N-substituted(meth)acrylamide lactones, (meth)acryliclactams, N-substituted(meth)acrylamide lactams, and glycidyl (meth)acrylate, and mixturesthereof.
 15. The multi-layer composite coating of claim 1, wherein theone or more polymerizable monomers having functional groups which arecapable of reacting to form crosslinks (3) are present in the monomericcomposition in an amount ranging from 0.5 to 8 percent by weight basedon total weight of monomers present in the monomeric composition. 16.The multi-layer composite coating of claim 15, wherein the one or morepolymerizable monomers having functional groups which are capable ofreacting to form crosslinks (3) is present in the monomeric compositionin an amount ranging from 1 to 5 percent by weight based on total weightof monomers present in the monomeric composition.
 17. The multi-layercomposite coating of claim 1, wherein the one or more polymerizable,ethylenically unsaturated monomers (4) are present in the monomericcomposition in an amount ranging from 0.5 to 50 percent by weight basedon total weight of monomers present in the monomeric composition. 18.The multi-layer composite coating of claim 17, wherein the one or morepolymerizable, ethylenically unsaturated monomers (4) are present in themonomeric composition in an amount ranging from 20 to 40 percent byweight based on total weight of monomers present in the monomericcomposition.
 19. The multi-layer composite coating of claim 1, whereinthe polymeric microparticles have an average particle size ranging from800 to 10,000 Angstroms.
 20. The multi-layer composite coating of claim1, wherein the aqueous dispersion of polymeric microparticles is presentin the topcoat film-forming composition an amount ranging from 1.0 to 20percent by weight based on total weight of resin solids present in thetopcoat film-forming composition.
 21. The multi-layer composite coatingof claim 20, wherein the aqueous dispersion of polymeric microparticlesis present in the topcoat film-forming composition an amount rangingfrom 1.0 to 15 percent by weight based on total weight of resin solidspresent in the topcoat film-forming composition.
 22. The multi-layercomposite coating of claim 1, wherein the topcoat film-formingcomposition comprises a thermosetting composition.
 23. The multi-layercomposite coating of claim 1, wherein the topcoat film-formingcomposition comprises a thermoplastic composition.
 24. The multi-layercomposite coating of claim 22, wherein the topcoat film-formingcomposition further comprises (a) a resinous binder system comprising areactive functional group-containing polymer, and (b) a crosslinkingagent having functional groups reactive with the functional groups ofthe polymer.
 25. The multi-layer composite coating of claim 24, whereinthe resinous binder (a) comprises a second aqueous dispersion ofpolymeric microparticles.
 26. The multi-layer composite coating of claim25, wherein the second aqueous dispersion of polymeric microparticlescomprises: (i) at least one substantially hydrophobic polymer havingreactive functional groups; and (ii) at least one substantiallyhydrophobic crosslinking agents having functional groups reactive withthe functional groups of the polymer (i).
 27. A substrate comprising asubstrate, and the multi-layer composite coating of claim 1 over atleast a portion of the substrate.
 28. A multi-layer composite coatingcomprising a basecoat deposited from at least one basecoat film-formingcomposition and a topcoat composition applied over at least a portion ofthe base coat in which the topcoat is deposited from at least onetopcoat film forming composition that is substantially free of organicsolvent, the topcoat film-forming composition comprising: an aqueousdispersion of polymeric microparticles prepared by emulsionpolymerization of a monomeric composition consisting of: (1) at least 10percent by weight of one or more vinyl aromatic compounds; (2) 0.1 to 10percent by weight of one or more carboxylic acid functionalpolymerizable, ethylenically unsaturated monomers; (3) 0 to 10 percentby weight of one or more polymerizable monomers having one or morefunctional groups which are capable of reacting to form crosslinks; and(4) one or more polymerizable, ethylenically unsaturated monomers, wherethe weight percentages are based on total weight of monomers present inthe monomeric composition; wherein each of (1), (2), (3) and (4) aredifferent one from the other and wherein at least one of (3) and (4) ispresent in the monomeric composition; and wherein the topcoatfilm-forming composition comprises a material comprising areactive-functional group-containing polysiloxane; and wherein thematerial comprising the reactive-functional group-containingpolysiloxane is a second water dilutable additive that is different fromthe polymeric microparticles of the aqueous dispersion.